Kiln head waste heat utilization system

Abstract

The invention provides a kiln head waste heat utilization system, and relates to the technical field of cement production, the kiln head waste heat utilization system comprises a rotary kiln, a grate cooler, a coal milling system and a waste heat boiler, the rotary kiln comprises a barrel, a kiln head combustor and a decomposing furnace, and the interior of the grate cooler is divided into a high-temperature section, a medium-temperature section and a low-temperature section; the kiln head waste heat utilization system further comprises a grate cooler air collecting box, a coal mill circulating air unit and a waste heat power generation air circulating unit; the kiln head waste heat utilization system cancels a coal mill waste gas discharge coal mill chimney; an outlet of the grate cooler air collecting box is connected with an inlet of a medium-temperature section of the grate cooler; the gas entering the coal mill system passes through the coal mill circulating air consumption unit and then enters the grate cooler air collecting box for recycling; the waste heat power generation air circulation unit at least comprises a first waste heat power generation air sub-circulation unit, and part of gas entering the waste heat boiler enters the grate cooler air collecting box through the first waste heat power generation air sub-circulation unit to be recycled. The effects of reducing air consumption, reducing waste gas emission and recovering waste heat of waste gas are achieved.

Description

Technical Field

[0001] The present application relates to the technical field of cement production, and in particular to a kiln head waste heat utilization system. Background Art

[0002] For ultra-low emission retrofits at cement plants, controlling air consumption at the source and exhaust emissions at the end of the process are equally important. Only by effectively controlling air consumption can exhaust emissions be fundamentally reduced. If equipment air leakage is eliminated, the air used to burn clinker in the rotary kiln comes from two sources: the grate cooler cooling fan and the burner. Reducing air consumption in these two locations is the fundamental starting point for reducing air consumption. Heat recovery or waste heat utilization should be considered based on this foundation during cement production and design.

[0003] Currently, all air drawn in by the burner enters the kiln for coal combustion. A portion of the air drawn in by the grate cooler enters the kiln for coal combustion, while the remainder is exhausted. This exhaust air is divided into three parts: The first part enters the coal mill system to dry the coal. After purification in the dust collector, it is discharged through a separate chimney. The flue gas temperature is 60-80°C, and the air volume accounts for approximately 6%-10% of the total air supply. The second part enters the waste heat power generation system to recover heat. After purification in the kiln head dust collector, it is discharged. The flue gas temperature is 90-150°C, and the air volume accounts for approximately 15%-20% of the total air supply. The third part is the residual air, which merges with the waste heat power generation air and is directly discharged. The flue gas temperature is 90-150°C, and the air volume accounts for approximately 25%-30% of the total air supply. That is to say, about 50% of the air resources are wasted, and the accompanying heat is also discharged. This part of heat energy is equivalent to 5kg of standard coal per ton of clinker. The actual production capacity of a 5,000t / d clinker production line is about 6,000t / d. Calculated based on 300 operating days per year, it is equivalent to burning 9,000 tons of standard coal a year.

[0004] The invention patent with the Chinese patent publication number "CN111792859 A" discloses "a cement production system that reduces heat loss on the surface of the kiln shell and eliminates heat loss at the kiln head". In terms of flue gas circulation, it has two circulations. One is to treat the exhaust air of the coal mill system as the primary air and enter the kiln head burner, which can be called the coal mill air circulation; the other is to return the waste heat power generation air and the waste air to the grate cooler, or to return a part of it to the coal mill system, which can be called the 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 there are the following problems: (1) The main purpose of the coal mill air is to dry the moisture in the raw coal, prevent moisture from entering the kiln, and reduce the heat loss caused by the absorption of heat and temperature rise due to moisture evaporation. However, the flue gas after drying the coal mill in this patent is entered into the kiln as the primary air, which will bring moisture into the kiln head burner, and does not eliminate the heat loss caused by moisture, which is equivalent to not achieving the drying purpose of the coal mill. (2) The air used for waste heat power generation is recycled to cool the clinker in the medium temperature section of the grate cooler. In contrast, the flue gas temperature at the grate cooler inlet rises, and the clinker temperature also rises accordingly. In order to ensure that the temperature of the clinker out of the kiln does not rise and the waste heat power generation inlet temperature does not decrease, it is necessary to increase the amount of cold air added to the low temperature section of the grate cooler. In other words, there must be waste air discharged. The flue gas cannot be circulated in an infinite closed loop, the chimney at the kiln head cannot be eliminated, and the heat 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 full-circulation grate cooler with residual air". Strictly speaking, it is an air circulation system for waste heat power generation, but does not consider the air circulation for coal mills. There is also the problem of increasing the amount of cold air in the low-temperature section of the grate cooler, and the residual air must be discharged externally, which cannot achieve the purpose of full circulation of the residual air.

[0006] In summary, it is impossible to recycle all the wind used for waste heat power generation. On this basis, it is an urgent problem to consider how to make full use of flue gas circulation to reduce air consumption, reduce waste gas emissions and recover waste heat from waste gas. Summary of the Invention

[0007] The purpose of this application is to provide a kiln head waste heat utilization system, aiming 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 the present 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 the present application.

[0009] According to a first aspect of the present application, a kiln head waste heat utilization system is provided, comprising a rotary kiln, a grate cooler, a coal mill system, a waste heat boiler, and a pulverized coal conveying unit. The rotary kiln comprises a cylinder, a kiln head burner, and a calciner. The interior of 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 the clinker. The high-temperature gas from the high-temperature section enters the cylinder and the calciner as secondary and tertiary air, respectively. The medium-temperature section is connected to the coal mill system and the waste heat boiler via outlets.

[0010] The kiln head waste heat utilization system also includes a grate cooler wind box, a coal mill circulation 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 coal mill chimney;

[0011] The outlet of the grate cooler wind box is connected to the inlet of the medium temperature section of the grate cooler;

[0012] One end of the coal mill circulation air unit is connected to the outlet of the coal mill system, and the other end is connected to the inlet of the grate cooler wind box; the coal mill circulation air unit is configured so that the gas entering the coal mill system passes through the coal mill circulation air unit and then enters the grate cooler wind box for circulation;

[0013] The wind circulation unit for waste heat power generation includes at least a first wind sub-circulation unit for waste heat power generation, and the first wind sub-circulation unit for waste heat power generation is configured so that part of the gas entering the waste heat boiler enters the grate cooler wind box through the first wind sub-circulation unit for waste heat power generation for circulation.

[0014] In an exemplary embodiment of the present application, 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 connected in sequence between the coal mill system and the grate cooler wind box through connecting pipes.

[0015] In an exemplary embodiment of the present application, the coal mill dust collector can filter part of the coal powder in the gas flowing through, and the coal mill system can make the gas flowing through contain moisture. The moisture and the coal powder remaining after filtering by the coal mill dust collector are recycled through the grate cooler wind box and then enter the medium temperature section of the grate cooler.

[0016] In an exemplary embodiment of the present application, the wind circulation unit for waste heat power generation further includes a second wind sub-circulation unit for waste heat power generation and a third wind sub-circulation unit for waste heat power generation;

[0017] The second wind subcirculation unit for waste heat power generation is configured such that a portion of the gas entering the waste heat boiler enters the pulverized coal conveying unit through the second wind subcirculation unit for waste heat power generation and then enters the rotary kiln and the decomposition furnace along with the pulverized coal;

[0018] The third wind sub-circulation unit for waste heat power generation is configured so that a portion of the gas entering the waste heat boiler enters the kiln head burner through the third wind sub-circulation unit for waste heat power generation and is used as primary air.

[0019] In an exemplary embodiment of the present application, the first wind circulation unit for waste heat power generation includes a kiln head dust collector, a kiln head exhaust fan, a wind circulation valve for waste heat power generation and connecting pipes. The kiln head dust collector, kiln head exhaust fan and wind circulation valve for waste heat power generation are connected in sequence between the outlet of the waste heat boiler and the inlet of the grate cooler wind box through connecting pipes.

[0020] In an exemplary embodiment of the present application, the second wind power generation wind subcirculation unit is connected between the kiln head exhaust fan and the kiln head burner;

[0021] The wind circulation unit for the second surplus wind power generation includes an air intake valve, a coal powder conveying intake valve, a coal powder conveying wind box, a kiln tail coal powder blower, a kiln head coal powder blower and connecting pipe fittings. The air intake valve is connected to the inlet of the coal powder conveying wind box, one end of the coal powder conveying intake valve is connected to the outlet of the kiln head exhaust fan through a connecting pipe fitting, and the other end is connected to the inlet of the coal powder conveying wind box, one end of the kiln tail coal powder blower is connected to the outlet of the coal powder conveying wind box through a connecting pipe fitting, and the other end is connected to the decomposition furnace through a kiln tail coal powder scale through a connecting pipe fitting, and one end of the kiln head coal powder blower is connected to the outlet of the coal powder conveying wind box through a connecting pipe fitting, and the other end is connected to the kiln head burner through a connecting pipe fitting through a kiln head coal powder scale.

[0022] In an exemplary embodiment of the present application, the third wind subcirculation unit for surplus wind power generation is connected between the kiln head exhaust fan and the primary air inlet of the kiln head burner;

[0023] The third wind sub-circulation unit for surplus wind power generation includes a kiln head primary fan and a connecting pipe. One end of the kiln head primary fan is connected to the outlet of the kiln head exhaust fan through the connecting pipe, and the other end is connected to the primary air inlet of the kiln head burner through the connecting pipe.

[0024] In an exemplary embodiment of the present application, a waste heat power generation air exhaust system is further included, the waste heat power generation air exhaust system includes a kiln head chimney and a connecting pipe, the kiln head chimney is connected to the kiln head exhaust fan through the connecting pipe;

[0025] The remaining gas after the gas entering the waste heat boiler is distributed by the first waste heat power generation wind sub-circulation unit, the second waste heat power generation wind sub-circulation unit and the third waste heat power generation wind sub-circulation unit enters the kiln head chimney and is discharged.

[0026] In an exemplary embodiment of the present application, the low-temperature section of the grate cooler is provided with an outlet, and the low-temperature gas of the low-temperature section merges with the gas at the outlet of the waste heat boiler through the outlet and the connecting pipe and then enters the kiln head dust collector.

[0027] In an exemplary embodiment of the present application, a clinker conveying unit is further included, which includes a clinker conveyor, a clinker storage and connecting pipes. After the clinker in the grate cooler exchanges heat with the gas, the clinker falls onto the clinker conveyor and is transported to the clinker storage by the clinker conveyor; the temperature of the clinker decreases during transportation by the clinker conveyor, and the connecting pipes are located above the clinker conveyor, and the connecting pipes located above the clinker conveyor are connected to the connecting pipes at the outlet of the waste heat boiler.

[0028] The exemplary embodiments of the present application may have some or all of the following beneficial effects:

[0029] 1. In a kiln head waste heat utilization system provided in an example embodiment of the present application, part of the gas from the medium 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 part is introduced into the coal mill system to form coal mill air for its use, so that the kiln head waste heat utilization system can fully utilize the heat of the medium temperature section of the grate cooler. After the waste heat boiler discharges the used gas, the first waste heat power generation air sub-circulation unit in the waste heat power generation air circulation unit can recycle part of the air flow discharged after use by the waste heat boiler into the grate cooler manifold; and the coal mill circulation air unit can recycle all the coal mill air used by the coal mill system into the grate cooler manifold, and the grate cooler manifold will mix the two recycled air flows and then transport them to the medium temperature section of the grate cooler. Specifically, the moisture carried by the coal mill air when drying the raw coal will be recycled into the grate cooler. The evaporation and heat absorption of the moisture in the grate cooler will further accelerate the cooling of the clinker, thereby improving the cooling efficiency of the medium-temperature section of the grate cooler. Compared with the existing technology, no moisture is brought into the kiln head burner, thereby not causing heat loss to the temperature inside the kiln head burner. In this application, the coal mill air is introduced into the grate cooler, which not only does not cause heat loss to the kiln head burner, but also helps to improve the grate cooler's cooling efficiency for the clinker. Therefore, the kiln head waste heat utilization system in this application achieves the effects of reducing air consumption, reducing exhaust gas emissions, and recovering waste heat from exhaust gas;

[0030] 2. In a kiln head waste heat utilization system provided in an example embodiment of the present application, when the coal mill air is discharged from the coal mill system, the coal mill air will carry moisture and coal powder; when the coal mill air passes through the coal mill dust collector, the coal mill dust collector will filter out most of the coal powder in the coal mill air, but the gas discharged from the coal mill dust collector will still contain a small amount of coal powder and moisture. The coal powder not filtered out by the coal mill dust collector will mix with the moisture to form wet coal powder, and this part of the wet coal powder will enter the medium temperature section of the grate cooler together with the recovered coal mill air. The wet coal powder continues to rise in the medium temperature section of the grate cooler with the flow of air. During the rising process, the moisture continues to evaporate, causing the coal powder to gradually dry, and it can absorb a large amount of heat from the clinker, thereby improving the cooling effect on the clinker; when the coal powder rises to before entering the waste heat boiler and the coal mill system, the temperature in the grate cooler will cause the coal powder to burn, thereby increasing the temperature of the gas entering the waste heat boiler and the coal mill system. The above structure can, on the one hand, prevent the coal powder 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 powder to increase the temperature of the gas entering the waste heat boiler and coal mill system, thereby improving the heat utilization rate.

[0031] 3. In a kiln head waste heat utilization system provided in an exemplary embodiment of the present application, a second waste heat power generation wind sub-circulation unit in the waste heat power generation wind circulation unit can transport part of the airflow discharged from the waste heat boiler to the pulverized coal conveying unit, and then transport the pulverized coal to the kiln head burner and decomposition furnace respectively. Compared with the prior art method of using external air to transport pulverized coal, the waste heat power generation wind will have a certain amount of heat, so when it enters the kiln head burner and decomposition furnace, it can achieve the effect of heat recovery and utilization;

[0032] 4. In a kiln head waste heat utilization system provided in an example embodiment of the present application, through the third waste heat power generation wind sub-circulation unit in the waste heat power generation wind sub-circulation unit, the third waste heat power generation wind sub-circulation unit can introduce part of the air flow discharged from the waste heat boiler into the kiln head burner for use as primary air, thereby further improving the heat utilization rate of the system.

[0033] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0035] Figure 1 A schematic diagram of a kiln head waste heat utilization system in an embodiment of the present application is shown.

[0036] Description of reference numerals:

[0037] 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. Pulverized coal silo at the kiln end; 15. Pulverized coal silo at the kiln end; 16. Pulverized coal scale at the kiln end; 17. Pulverized coal scale at the kiln end; 18. Precalciner; 19. Kiln Head burner; 20. Pulverized coal blower at the kiln tail; 21. Pulverized coal standby blower; 22. Pulverized coal blower at the kiln head; 23, 24. Primary fans at the kiln head; 25-36. Cooling fans; 37. Grate cooler manifold; 37-1. Air circulation valve for waste heat power generation; 37-2. Air circulation valve for coal mill; 38. Pulverized coal conveying manifold; 38-1. Air intake valve; 38-2. Pulverized coal conveying intake valve. DETAILED DESCRIPTION

[0038] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example 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 concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent like or similar structures, and thus their detailed descriptions will be omitted. Furthermore, the figures are merely schematic illustrations of the present application and are not necessarily drawn to scale.

[0039] While relative terms such as "upper" and "lower" are used in this specification to describe the relationship of one illustrated component to another, these terms are used for convenience only, such as in accordance with the orientation of the illustrations in the accompanying drawings. It should be understood that if the illustrated device were flipped upside down, the component described as "upper" would become the component "lower." When a structure is referred to as "on" another structure, this may mean that the structure is integrally formed with the other structure, that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure through the other structure.

[0040] The terms "a", "an", "the" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express open-ended inclusion and mean that additional elements / components / etc. may be present in addition to the listed elements / components / etc.; the terms "first" and "second" are used only as labels and do not limit the quantity of their objects.

[0041] like Figure 1 As shown, in an embodiment of the present application, a kiln head waste heat utilization system is disclosed, including a rotary kiln 1, a grate cooler 2, a coal grinding system 5, and a waste heat boiler 6.

[0042] Furthermore, the rotary kiln 1 includes a cylinder, a kiln head burner 19 and a decomposition furnace 18; 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 temperature after the gas and clinker are heat exchanged. The high-temperature gas in the high-temperature section enters the cylinder and the decomposition furnace 18 as secondary and tertiary air respectively, and the medium-temperature section is connected to the coal grinding system 5 and the waste heat boiler 6 respectively by opening 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 referred to as waste heat power generation air, and the gas entering the coal grinding system 5 from the medium-temperature section of the grate cooler 2 can be referred to as coal grinding air.

[0043] The kiln head waste heat utilization system also includes a grate cooler wind box 37, a coal mill circulation 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 coal mill chimney;

[0044] The outlet of the grate cooler wind box 37 is connected to the inlet of the medium temperature section of the grate cooler 2;

[0045] One end of the coal mill circulation 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 wind box 37; the coal mill circulation air unit is configured so that the gas entering the coal mill system 5 passes through the coal mill circulation air unit and then enters the grate cooler wind box 37 for recycling;

[0046] The wind circulation unit for waste heat power generation includes at least a first wind sub-circulation unit for waste heat power generation, and the first wind sub-circulation unit for waste heat power generation is configured so that part of the gas entering the waste heat boiler 6 enters the grate cooler wind box 37 for recycling through the first wind sub-circulation unit for waste heat power generation.

[0047] In the embodiment of the present application, grate cooler 2 draws air from the outside into its interior during the high-temperature section to cool the clinker. The gas in the medium-temperature section of grate cooler 2 enters the coal mill system 5, while the remaining gas enters the waste heat boiler 6 for use. This process effectively utilizes the heat in the medium-temperature section of grate cooler 2. The waste heat boiler 6 uses the heat energy from the medium-temperature section of grate cooler 2 for power generation or heating, reducing external energy demand. The coal mill system 5 recovers heat energy, accelerating the evaporation of moisture from the raw coal and drying the resulting pulverized coal. Furthermore, this process reduces direct heat emissions and minimizes thermal pollution to the environment.

[0048] In the embodiment of the present application, the coal mill system 5 discharges the used gas, and then discharges the gas into the grate cooler wind box 37 through the coal mill circulation air unit; in the prior art, the coal mill system 5 usually discharges the gas directly through the coal mill chimney. Compared with the prior art, the kiln head waste heat utilization system disclosed in the present application eliminates the coal mill chimney used to discharge the coal mill waste gas, and instead guides all the coal mill waste gas into the grate cooler wind box 37, and then from the grate cooler wind box 37 to the medium temperature section of the grate cooler 2 for recycling. Therefore, in this system, all the coal mill waste discharged from the coal mill system 5 can be recycled and utilized without being discharged. On the one hand, it effectively reduces the waste of resources, and on the other hand, it plays a good role in protecting the environment and reduces pollution to the environment.

[0049] In the embodiment of the present application, the coal mill circulating air unit includes a coal mill dust collector 10, a coal mill exhaust fan 11, and a coal mill air circulating air valve 37-2; the coal mill dust collector 10, the coal mill exhaust fan 11 and the coal mill air circulating air valve 37-2 are connected in sequence between the coal mill system 5 and the grate cooler wind box 37 through connecting pipes.

[0050] In the present application, when the coal mill system 5 prepares coal powder, the heat energy in the grate cooler 2 can be used to dry the coal powder to remove the moisture contained in the coal powder. The gas discharged from the coal mill system 5 will carry the moisture evaporated from the coal powder. Then it enters the coal mill dust collector 10, which is used to capture part of the coal powder dust generated by the coal mill system 5. Since the coal mill dust collector 10 needs to allow the gas to pass through and be discharged, and the coal powder dust cannot block the flow of the gas, this results in the coal mill dust collector 10 only filtering out most of the coal powder in the gas, and a small amount of coal powder cannot be completely filtered. 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 certain pollution to the environment.

[0051] In the embodiment of the present application, the gas exhausted from the coal mill dust collector 10 is further discharged through the coal mill exhaust fan 11, the exhaust end of which is connected to the grate cooler manifold 37 via a connecting pipe. In this application, the gas exhausted from the coal mill circulating air unit to the grate cooler manifold 37 is referred to as the coal mill circulating airflow; the coal mill circulating airflow will carry moisture mixed with the pulverized coal to form wet pulverized coal.

[0052] After the coal mill circulating airflow enters the grate cooler manifold 37, it is discharged into the medium temperature section of the grate cooler 2 through the connecting pipe. The mixed airflow discharged into the grate cooler 2 will carry wet coal powder. In the medium temperature section of the grate cooler 2, the coal powder carried by the airflow will first be dried, causing the moisture to evaporate, thereby absorbing a large amount of heat, thereby improving the cooling effect on the clinker. As the airflow flows in the grate cooler 2, the coal powder also rises continuously. The heat from the grate cooler 2 causes the coal powder to burn when it enters the waste heat boiler 6 and the coal mill system 5, thereby increasing the temperature of the air used for waste heat power generation and the air used for the coal mill, thereby improving the thermal utilization rate of the waste heat boiler 6 and the coal mill system 5.

[0053] In summary, redirecting the coal mill circulating airflow to the medium-temperature section of grate cooler 2 not only improves the clinker cooling effect of grate cooler 2 but also heats the gas flowing through waste heat boiler 6 and coal mill system 5, improving the thermal efficiency of both. More importantly, pulverized coal that fails to filter in coal mill dust collector 10 can be redirected to grate cooler 2 for combustion, rather than being discharged into the atmosphere, thus protecting the environment.

[0054] In an embodiment of the present application, the kiln head waste heat utilization system also includes an air intake unit, an air exhaust system for waste heat power generation, and a clinker conveying unit.

[0055] The air intake unit includes a grate cooler wind box 37, cooling fans 25-36 and connecting pipes; cooling fans 25-28 are arranged in the high-temperature section of the grate cooler 2, for transporting air to the high-temperature section of the grate cooler 2; cooling fans 29-34 are arranged in the medium-temperature section of the grate cooler 2, for transporting the mixed air flow derived from the grate cooler wind box 37 to the medium-temperature section of the grate cooler 2; cooling fans 35 and 36 are arranged in the low-temperature section of the grate cooler 2, for transporting air to the low-temperature section of the grate cooler 2.

[0056] In the embodiment of the present application, the first wind subcirculation unit for waste heat power generation includes a kiln head dust collector 7, a kiln head exhaust fan 8 and a waste heat power generation wind circulation air valve 37-1;

[0057] The kiln head dust collector 7, kiln head exhaust fan 8 and waste heat power generation air circulation valve 37-1 are sequentially connected between the outlet of the waste heat boiler 6 and the inlet of the grate cooler wind box 37 through connecting pipes.

[0058] In the embodiment of the present application, the gas that enters the grate cooler manifold 37 for recycling after passing through the first waste heat power generation wind subcirculation unit is referred to as the waste heat power generation circulating airflow. Specifically, the gas exhausted from the medium-temperature section of the grate cooler 2 enters the waste heat boiler 6 for use, is then discharged from the waste heat boiler 6, and after being filtered by the kiln head dust collector 7, a portion of the gas is discharged to the grate cooler manifold 37 via the kiln head exhaust fan 8. The gas discharged into the grate cooler manifold 37 is referred to as 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 manifold 37 before being discharged into the medium-temperature section of the grate cooler 2.

[0059] In the embodiment of the present application, the kiln head waste heat utilization system also includes a pulverized coal conveying unit. Specifically, the pulverized coal conveying unit includes: a pulverized coal conveyor 13, a pulverized coal silo 14 at the kiln end, a pulverized coal silo 15 at the kiln end, a pulverized coal scale 16 at the kiln end, a pulverized coal scale 17 at the kiln end, a pulverized coal conveying manifold 38, a pulverized coal blower 20 at the kiln end, a pulverized coal standby blower 21, a pulverized coal blower 22 at the kiln end, a kiln head burner 19, and connecting pipes.

[0060] The pulverized coal flows as follows: After being ground into pulverized coal by the coal mill system 5, it is collected by the coal mill dust collector 10 and fed via the pulverized coal conveyor 13 into the kiln tail coal silo 14 and the kiln head coal silo 15, respectively. The kiln tail coal is measured by the kiln tail coal scale 16 and then carried by the wind into the decomposition furnace 18. The kiln head coal is measured by the kiln head coal scale 17 and then carried by the wind into the kiln head burner 19.

[0061] In an embodiment of the present application, the wind circulation unit for waste heat power generation also includes a second wind sub-circulation unit for waste heat power generation. The second wind sub-circulation unit for waste heat power generation is configured so that a portion of the gas entering the waste heat boiler 6 enters the pulverized coal conveying unit through the second wind sub-circulation unit for waste heat power generation and then enters the rotary kiln 1 and the decomposition furnace 18 respectively with the pulverized coal.

[0062] Furthermore, the second wind subcirculation unit for residual wind power generation includes an air intake valve 38 - 1 , a pulverized coal conveying intake valve 38 - 2 , a pulverized coal conveying wind box 38 , a kiln tail pulverized coal blower 20 , and a kiln head pulverized coal blower 22 .

[0063] Furthermore, the air intake valve 38-1 is connected to the inlet of the coal powder conveying wind box 38. When the air intake valve 38-1 is opened, outside air can enter the coal powder conveying wind box 38; one end of the coal powder conveying air intake valve 38-2 is connected to the outlet of the kiln head exhaust fan 8 through a connecting pipe, and the other end is connected to the inlet of the coal powder conveying wind box 38. One end of the kiln tail coal powder blower 20 is connected to the outlet of the coal powder conveying wind box 38 through a connecting pipe, and the other end is connected to the decomposition furnace 18 through the kiln tail coal powder scale 16 through a connecting pipe. One end of the kiln head coal powder blower 22 is connected to the outlet of the coal powder conveying wind box 38 through a connecting pipe, and the other end is connected to the kiln head burner 19 through a connecting pipe through the kiln head coal powder scale 17.

[0064] Furthermore, the second wind sub-circulation unit for surplus wind power generation also includes a pulverized coal standby blower 21, a three-way pipe, and an air valve. The three-way pipe includes a main pipe and two branch pipes. The main pipe is connected to the exhaust end of the pulverized coal standby blower 21, one of the branch pipes is connected to the connecting pipe fitting at the exhaust end of the kiln head pulverized coal blower 22, and the other branch pipe is connected to the connecting pipe fitting at the exhaust end of the kiln tail pulverized coal blower 20. Two air valves are provided, and the two air valves are installed on the two branch pipes. The pulverized coal standby blower 21 achieves the effect of "two in use and one in reserve". 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 can be opened to continue working.

[0065] Specifically, the kiln head exhaust fan 8 discharges part of the gas to the coal powder conveying wind box 38, and the coal powder conveying wind box 38 mixes this part of the gas with the outside air and then discharges it. The discharged gas is called the coal powder conveying airflow; part of the coal powder conveying airflow flows to the kiln tail coal powder scale 16 through the connecting pipe fittings, and the other part of the airflow flows to the kiln head coal powder scale 17 through the connecting pipe fittings; the airflow flowing to the kiln tail coal powder scale 16 is called the kiln tail airflow, and the airflow flowing to the kiln head coal powder scale 17 is called the kiln head airflow; the kiln tail airflow introduces the coal powder on the kiln tail coal powder scale 16 into the decomposition furnace 18, and the kiln head airflow introduces the coal powder on the kiln head coal powder scale 17 into the kiln head burner 19.

[0066] In an embodiment of the present application, the wind circulation unit for waste heat power generation also includes a third wind sub-circulation unit for waste heat power generation. The third wind sub-circulation unit for waste heat power generation is configured so that a portion of the gas entering the waste heat boiler 6 enters the kiln head burner 19 through the third wind sub-circulation unit for waste heat power generation and is used as primary air.

[0067] Furthermore, a third wind sub-circulation unit for generating electricity from excess wind is connected between the kiln head exhaust fan 8 and the primary air inlet of the kiln head burner 19. The third wind sub-circulation unit for generating electricity from excess wind includes kiln head primary fans 23, 24 and connecting pipes. One end of the kiln head primary fans 23, 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 the present application, two kiln head primary fans 23, 24 are provided, and the two kiln head primary fans 23, 24 are configured as "one in use and one in reserve". During operation, only one of the kiln head primary fans 23 is activated. When the operating kiln head primary fan 23 fails, the other reserve kiln head primary fan 24 can be activated.

[0068] In the embodiment of the present application, the exhaust system for waste heat power generation includes a kiln head chimney 9 and connecting pipes, and the kiln head chimney 9 is connected to the kiln head exhaust fan 8 through the connecting pipes;

[0069] The remaining gas after the gas entering the waste heat boiler is distributed through the first waste heat power generation wind sub-circulation unit, the second waste heat power generation wind sub-circulation unit and the third waste heat power generation wind sub-circulation unit is discarded, and the discarded gas enters the kiln head chimney 9 and is discharged outside.

[0070] Therefore, in summary, the airflow direction in the kiln head waste heat utilization system of this application is as follows:

[0071] In addition to the outside air, the cooling air source of the grate cooler 2 is newly added from two places, namely the coal mill circulating air flow and the waste heat power generation circulating air flow. The two air flows enter the grate cooler 2 after passing through the grate cooler wind box 37; after the gas in the grate cooler 2 exchanges heat with the clinker, the high-temperature section gas enters the rotary kiln 1 and the decomposition furnace 18 as secondary air and tertiary air respectively, the medium-temperature section gas enters the coal mill system 5 and the waste heat boiler 6 respectively, and the low-temperature section 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, and the coal mill circulating airflow enters the grate cooler wind box 37 for recycling; the gas entering the waste heat boiler 6 passes through the waste heat power generation air circulation unit, and a part of it forms a waste heat power generation circulating airflow and enters the grate cooler wind box 37 for recycling; a part of it enters the coal powder conveying unit to form a coal powder conveying airflow, and then the coal powder conveying airflow passes through the connecting pipe to form a kiln head airflow flowing to the kiln head coal powder scale 17, and a kiln tail airflow flowing to the kiln tail coal powder scale 16. The kiln head airflow enters the kiln head burner 19 with the coal powder, and the kiln tail airflow enters the decomposition furnace 18 with the coal powder; another part enters the kiln head burner 19 for use as primary air; the remaining air is purified by the kiln head dust collector 7 and discharged by the kiln head exhaust fan 8 to the kiln head chimney 9 for external discharge.

[0072] In the embodiment of the present application, the kiln head waste heat utilization system also includes a clinker conveying unit, which includes a clinker conveyor 3 and a clinker storage 4. In this application, the clinker is transported as follows: After being processed in the rotary kiln 1, the high-temperature clinker directly enters the grate cooler 2. The grate cooler 2 drives the clinker away from the rotary kiln 1. During this movement, the clinker exchanges heat with the airflow, continuously reducing the clinker temperature. The interior of the grate cooler 2 can be divided into a high-temperature section, a medium-temperature section, and a low-temperature section, respectively, based on the clinker temperature as it moves away from the rotary kiln 1. Specifically, the high-temperature section has a temperature range of approximately 1200°C to 1000°C; the medium-temperature section has a temperature range of approximately 1000°C to 600°C; and the low-temperature section has a temperature range below 600°C. The discharge end of the grate cooler 2 is located at the end away from the rotary kiln 1. The cooled clinker is discharged from the discharge end of the grate cooler 2, and the clinker conveyor 3 transports the processed clinker to the clinker storage 4.

[0073] In the embodiment of the present application, the low-temperature section of the grate cooler 2 is provided with an outlet, and the low-temperature gas of the low-temperature section is merged with the gas at the outlet of the waste heat boiler 6 through the outlet and the connecting pipe and then enters the kiln head dust collector 7. These gases usually contain a certain amount of heat, and although the temperature is relatively low, they can still be recycled. The gas at the outlet of the waste heat boiler 6 is usually at a higher temperature. After mixing with the gas at the low-temperature section of the grate cooler 2, the gas temperature can be balanced, thus preventing the kiln head dust collector 7 from being damaged due to excessive temperature. Therefore, recycling the gas at the low-temperature section of the grate cooler 2 not only increases the recycled air volume, but also protects the kiln head dust collector 7.

[0074] In the embodiment of the present application, the clinker conveyor 3 is connected to the connecting pipe fitting of the outlet of the waste heat boiler 6 through a connecting pipe fitting after the clinker leaves the low-temperature section of the grate cooler 2. Specifically, a dust collecting hood is provided above the clinker conveyor 3, and the dust collecting hood is 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 to the gas at the outlet of the waste heat boiler 6 through the dust collecting hood and the connecting pipe fitting, and then filtered through the kiln head dust collector 7. On the one hand, the floating clinker can be filtered and recovered, which not only reduces the waste of clinker, but also protects the surrounding environment; on the other hand, it can further increase the amount of heat recovered.

[0075] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the embodiments of the present invention. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not covered by this application. The specification and embodiments are intended to be exemplary only, and the true scope and spirit of the present invention 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. The rotary kiln comprises a drum, a kiln head burner, and a calciner. The interior of the grate cooler is divided into a high-temperature section, a medium-temperature section, and a low-temperature section based on the temperature of the gas after heat exchange with clinker. The high-temperature gas from the high-temperature section serves as secondary and tertiary air, respectively, entering the drum and the calciner. The medium-temperature section is connected to the coal mill system and the waste heat boiler via outlets. It is characterized by: The kiln head waste heat utilization system also includes a grate cooler wind box, a coal mill circulation 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 coal mill chimney; The outlet of the grate cooler wind box is connected to the inlet of the medium temperature section of the grate cooler; One end of the coal mill circulation air unit is connected to the outlet of the coal mill system, and the other end is connected to the inlet of the grate cooler wind box; the coal mill circulation air unit is configured so that the gas entering the coal mill system passes through the coal mill circulation air unit and then enters the grate cooler wind box for circulation; The wind circulation unit for waste heat power generation includes at least a first wind sub-circulation unit for waste heat power generation, and the first wind sub-circulation unit for waste heat power generation is configured so that part of the gas entering the waste heat boiler enters the grate cooler wind box through the first wind sub-circulation unit for waste heat power generation for circulation.

2. The kiln head waste heat utilization system according to claim 1 is 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 air valve and connecting pipes. The coal mill dust collector, the coal mill exhaust fan and the coal mill air circulation air valve are sequentially connected between the coal mill system and the grate cooler wind box through 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 powder and moisture; the coal mill dust collector of the coal mill circulating air unit can filter part of the coal powder in the gas, and the remaining coal powder enters the grate cooler wind box after passing through the coal mill exhaust fan, coal mill air circulation air valve and corresponding connecting pipes, and then enters the grate cooler for internal recycling; the moisture enters the grate cooler wind box after passing through the coal mill exhaust fan, coal mill air circulation air valve and corresponding connecting pipes, and then enters the medium temperature section of the grate cooler for heat exchange.

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

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

6. The kiln head waste heat utilization system according to claim 5, characterized in that: The second wind circulation unit for generating electricity from excess wind is connected between the kiln head exhaust fan and the kiln head burner; The wind circulation unit for the second surplus wind power generation includes an air intake valve, a coal powder conveying intake valve, a coal powder conveying wind box, a kiln tail coal powder blower, a kiln head coal powder blower and connecting pipe fittings. The air intake valve is connected to the inlet of the coal powder conveying wind box, one end of the coal powder conveying intake valve is connected to the outlet of the kiln head exhaust fan through a connecting pipe fitting, and the other end is connected to the inlet of the coal powder conveying wind box, one end of the kiln tail coal powder blower is connected to the outlet of the coal powder conveying wind box through a connecting pipe fitting, and the other end is connected to the decomposition furnace through a kiln tail coal powder scale through a connecting pipe fitting, and one end of the kiln head coal powder blower is connected to the outlet of the coal powder conveying wind box through a connecting pipe fitting, and the other end is connected to the kiln head burner through a connecting pipe fitting through a kiln head coal powder scale.

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

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

9. The kiln head waste heat utilization system according to claim 7, characterized in that: The low-temperature section of the grate cooler is provided with an outlet, and the low-temperature gas of the low-temperature section is merged with the gas of the waste heat boiler outlet through the outlet and the connecting pipe and then enters 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 storage and connecting pipes. After the clinker in the grate cooler exchanges heat with the gas, the clinker falls onto the clinker conveyor and is transported to the clinker storage by the clinker conveyor for storage. The temperature of the clinker decreases during transportation by the clinker conveyor. The connecting pipes are located above the clinker conveyor, and the connecting pipes located above the clinker conveyor are connected to the connecting pipes at the outlet of the waste heat boiler.

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