Kiln head waste heat utilization method

Abstract

The invention provides a kiln head waste heat utilization method and relates to the technical field of cement production, a kiln head waste heat utilization system is used, the kiln head waste heat utilization system comprises a coal mill circulating air unit and a waste heat power generation air circulating unit, and the coal mill circulating air unit is connected between a coal mill system and a grate cooler air collecting box. The waste heat power generation wind circulation unit at least comprises a first waste heat power generation wind sub-circulation unit, and the kiln head waste heat utilization system cancels a coal mill waste gas discharge coal mill chimney; the kiln head waste heat utilization method comprises the following steps that smoke entering a coal mill system passes through a coal mill circulating air unit and then enters a grate cooler air collecting box to be recycled through the coal mill circulating air unit; a part of smoke entering the waste heat boiler enters an air collecting box of the grate cooler for recycling through the first waste heat power generation air sub-circulation unit by means of the first waste heat power generation air sub-circulation unit. The problems of reducing air consumption, reducing waste gas emission and recovering waste heat of waste gas are solved.

Description

Technical Field

[0001] The present application relates to the technical field of cement production, and in particular to a method for utilizing waste heat from a kiln head. 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 method for utilizing waste heat from a kiln head, aiming to solve the problem 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 method is provided, using a kiln head waste heat utilization system, the kiln head waste heat utilization system comprising a rotary kiln, a grate cooler, a coal mill system, a waste heat boiler, a pulverized coal conveying unit, a grate cooler wind box, a coal mill circulation air unit and a waste heat power generation air circulation unit, the outlet of the grate cooler wind box is connected to the inlet of the medium temperature section of the grate cooler, the medium temperature section is connected to the coal mill system and the waste heat boiler respectively by opening an outlet, the coal mill circulation air unit is connected between the coal mill system and the grate cooler wind box, the waste heat power generation air circulation unit comprises at least a first waste heat power generation wind sub-circulation unit connected between the waste heat boiler and the grate cooler wind box, and the kiln head waste heat utilization system eliminates the coal mill exhaust gas discharge coal mill chimney;

[0010] The kiln head waste heat utilization method comprises the following steps:

[0011] The coal mill circulating air unit is used to pass the flue gas entering the coal mill system through the coal mill circulating air unit and then enter the grate cooler wind box for recycling;

[0012] A portion of the flue gas entering the waste heat boiler is fed into the grate cooler wind box through the first wind circulation unit for waste heat power generation for recycling.

[0013] 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 circulating air valve and a connecting pipe fitting, wherein the coal mill dust collector, the coal mill exhaust fan and the coal mill air circulating air valve are sequentially connected between the coal mill system and the grate cooler wind box through the connecting pipe fitting;

[0014] The steps of using the coal mill circulating air unit to pass the flue gas entering the coal mill system through the coal mill circulating air unit and then enter the grate cooler wind box for recycling include:

[0015] The flue gas entering the coal mill system enters the coal mill dust collector through the connecting pipe for dust collection treatment;

[0016] The flue gas passing through the coal mill dust collector enters the grate cooler wind box for recycling through the coal mill air circulation valve under the power of the coal mill exhaust fan.

[0017] In an exemplary embodiment of the present application, the flue gas processed by the coal mill system contains a certain amount of moisture and coal powder;

[0018] Filtering part of the coal powder in the flue gas by using the coal mill dust collector;

[0019] The coal powder and moisture not filtered by the coal powder dust collector enter the grate cooler wind box after passing through the coal mill exhaust fan, coal mill air circulation valve and corresponding connecting pipes, and then enter the medium temperature section of the grate cooler for recycling.

[0020] 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;

[0021] The kiln head waste heat utilization method further comprises the following steps:

[0022] Using the second wind circulation unit for waste heat power generation, a portion of the flue gas entering the waste heat boiler enters the pulverized coal conveying unit through the second wind circulation unit for waste heat power generation, and then enters the rotary kiln and the decomposition furnace along with the pulverized coal;

[0023] The third wind subcirculation unit for waste heat power generation is used to allow part of the flue gas entering the waste heat boiler to enter the kiln head burner through the third wind subcirculation unit for waste heat power generation and be used as primary air.

[0024] In an exemplary embodiment of the present application, the first wind subcirculation unit for waste heat power generation includes a kiln head dust collector, a kiln head exhaust fan, a waste heat power generation air circulation valve and connecting pipes, and 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 wind box through the connecting pipes;

[0025] The step of using the first wind circulation unit for waste heat power generation to circulate a portion of the flue gas entering the waste heat boiler through the first wind circulation unit for waste heat power generation into the grate cooler wind manifold for use includes:

[0026] Part of the flue gas entering the waste heat boiler enters the kiln head dust collector through the connecting pipe for dust collection treatment, and then enters the grate cooler wind box for recycling through the air circulation valve for waste heat power generation under the power of the kiln head exhaust fan.

[0027] In an exemplary embodiment of the present application, the wind subcirculation unit for the second surplus wind power generation includes an air intake valve, a pulverized coal conveying intake valve, a pulverized coal conveying wind box, a kiln tail pulverized coal blower, a kiln head pulverized coal blower and a connecting pipe fitting, the air intake valve is connected to the inlet of the pulverized coal conveying wind box, one end of the pulverized coal 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 pulverized coal conveying wind box, one end of the kiln tail pulverized coal blower is connected to the outlet of the pulverized coal conveying wind box through a connecting pipe fitting, and the other end is connected to the decomposition furnace through a kiln tail pulverized coal scale through a connecting pipe fitting, the kiln head pulverized coal blower is connected to the outlet of the pulverized coal 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 pulverized coal scale;

[0028] The steps of the second wind subcirculation unit for waste heat power generation causing a portion of the flue gas entering the waste heat boiler to enter the pulverized coal conveying unit through the second wind subcirculation unit for waste heat power generation, and then respectively entering the rotary kiln and the decomposition furnace along with the pulverized coal include:

[0029] The flue gas passing through the kiln head dust collector enters the coal powder conveying wind box through the coal powder conveying air inlet valve under the power of the kiln head exhaust fan for recycling;

[0030] The outside air is allowed to enter the coal powder conveying wind box for circulation through the air intake valve;

[0031] A portion of the gas in the coal powder transport wind box is transported to the decomposition furnace through the coal powder scale at the kiln tail under the power of the coal powder blower at the kiln tail;

[0032] A portion of the gas in the coal powder transport wind box is transported to the kiln head burner through the kiln head coal powder scale under the power of the kiln head coal powder blower.

[0033] In an exemplary embodiment of the present application, the third wind subcirculation unit for surplus wind power generation includes a kiln head primary fan and a connecting pipe fitting, one end of the kiln head primary fan is connected to the outlet of the kiln head exhaust fan through the connecting pipe fitting, and the other end is connected to the primary air inlet of the kiln head burner through the connecting pipe fitting;

[0034] The steps of the third wind subcirculation unit for waste heat power generation transferring a portion of the flue gas entering the waste heat boiler into the kiln head burner as primary air through the third wind subcirculation unit for waste heat power generation include:

[0035] The flue gas passing through the kiln head dust collector is transported to the kiln head primary fan through the connecting pipe under the power of the kiln head exhaust fan; and then transported to the primary air inlet of the kiln head burner through the connecting pipe under the power of the kiln head primary fan.

[0036] In an exemplary embodiment of the present application, the kiln head waste heat utilization system further includes a waste heat power generation air exhaust system, which is configured to exhaust a portion of the flue gas entering the waste heat boiler through the waste heat power generation air exhaust system; the waste heat power generation air exhaust system includes a kiln head chimney and connecting pipes, and the kiln head chimney is connected to the kiln head exhaust fan via the connecting pipes;

[0037] The step of discharging a portion of the flue gas entering the waste heat boiler through the waste heat power generation air exhaust system includes:

[0038] The remaining flue gas distributed by the first wind sub-circulation unit for waste heat power generation, the second wind sub-circulation unit for waste heat power generation and the third wind sub-circulation unit for waste heat power generation is transported to the kiln head chimney through the connecting pipe to be discharged externally.

[0039] In an exemplary embodiment of the present application, an outlet is opened in the low-temperature section of the grate cooler, and the outlet of the grate cooler is connected to the outlet of the waste heat boiler through a connecting pipe;

[0040] The low-temperature flue gas discharged from the low-temperature section enters the connecting pipe of the waste heat boiler outlet through the connecting pipe fitting and merges with the flue gas passing through the waste heat boiler and then enters the kiln head dust collector together.

[0041] In an exemplary embodiment of the present application, the kiln head waste heat utilization system further includes a clinker conveying unit; the clinker conveying unit includes a clinker storage for storing clinker, a clinker conveyor for transporting clinker from the grate cooler to the clinker storage, and a connecting pipe located above the clinker conveyor, wherein the connecting pipe located above the clinker conveyor is connected to the connecting pipe located at the outlet of the waste heat boiler;

[0042] The heat emitted by the clinker conveyor when conveying clinker is recovered by utilizing the connecting pipe above the clinker conveyor;

[0043] The step of recovering the heat emitted by the clinker conveyor when conveying clinker by utilizing the connecting pipe above the clinker conveyor comprises:

[0044] After the clinker in the grate cooler exchanges heat with the gas, the clinker falls to the clinker conveyor;

[0045] The heat emitted by the clinker on the clinker conveyor is combined with the flue gas passing through the waste heat boiler through the connecting pipe and then enters the kiln head dust collector together.

[0046] The exemplary embodiments of the present application may have some or all of the following beneficial effects:

[0047] In a kiln head waste heat utilization method provided in an exemplary embodiment of this application, waste heat recovery and efficient utilization are achieved by diverting the gas from the medium-temperature section of the grate cooler. The system diverts the gas from the medium-temperature section of the grate cooler into two streams: one stream is directed to the waste heat boiler as power generation air, and the other stream is supplied to the coal mill system as drying air. This diversion design fully utilizes the heat from the medium-temperature section. Furthermore, a bidirectional circulation loop is constructed in this application: on the one hand, the waste heat power generation air circulation unit returns part of the exhaust air from the waste heat boiler to the grate cooler manifold via a first waste heat power generation air sub-circulation unit; on the other hand, the coal mill circulation air unit circulates all the air after use by the coal mill system back to the manifold. The two streams are then mixed in the manifold and re-enter the medium-temperature section of the grate cooler, forming a recycling system. This solution effectively reduces air consumption, reduces waste gas emissions, and fully recovers waste heat from the waste gas, ultimately improving the energy efficiency and environmental performance of the cement production line.

[0048] 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

[0049] 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.

[0050] Figure 1 A schematic diagram of a kiln head waste heat utilization system in an embodiment of the present application is shown.

[0051] Description of reference numerals:

[0052] 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

[0053] 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.

[0054] 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.

[0055] 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.

[0056] like Figure 1 As shown, in an embodiment of the present application, a kiln head waste heat utilization method using a kiln head waste heat utilization system is disclosed, and the kiln head waste heat utilization system includes a rotary kiln 1, a grate cooler 2, a coal grinding system 5, and a waste heat boiler 6.

[0057] 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 in descending order 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.

[0058] 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.

[0059] The outlet of the grate cooler wind box 37 is connected to the inlet of the medium temperature section of the grate cooler 2;

[0060] 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;

[0061] 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.

[0062] In the embodiment of the present application, the kiln head waste heat utilization method includes the following steps:

[0063] The flue gas entering the coal mill system 5 is recycled by the coal mill circulating air unit and then enters the grate cooler wind box 37;

[0064] A portion of the flue gas entering the waste heat boiler 6 is fed into the grate cooler wind manifold 37 through the first waste heat power generation wind circulation unit for recycling.

[0065] Specifically, the grate cooler 2 draws air from the outside into its interior during the high-temperature section to cool the internal clinker. Part of the gas in the medium-temperature section of the grate cooler 2 enters the coal mill system 5, and part enters the waste heat boiler 6 for use. In this process, the heat of the medium-temperature section of the grate cooler 2 is effectively utilized. The waste heat boiler 6 uses the heat energy of the medium-temperature section of the grate cooler 2 for power generation or heating, thereby reducing external energy demand. The coal mill system 5 recovers heat energy, which helps accelerate the evaporation of moisture in the raw coal and dries the resulting coal powder. Therefore, the above-mentioned solution effectively reduces air consumption, reduces waste gas emissions, and fully recovers waste heat from the waste gas, thereby improving the energy efficiency and environmental performance of the cement production line as a whole.

[0066] 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 method adopted by the present application eliminates the kiln head waste heat utilization system for discharging the coal mill exhaust gas to the coal mill chimney, and instead introduces all the coal mill exhaust gas into the grate cooler wind box 37, and then from the grate cooler wind box 37 into 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.

[0067] In the embodiment of the present application, the coal mill circulating air unit in the kiln head waste heat utilization system 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.

[0068] In the kiln head waste heat utilization method, the steps of utilizing the coal mill circulating air unit to pass the flue gas entering the coal mill system through the coal mill circulating air unit and then enter the grate cooler wind box for recycling include:

[0069] The flue gas entering the coal mill system enters the coal mill dust collector through the connecting pipe for dust collection treatment.

[0070] Specifically, 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. It then enters the coal mill dust collector 10, which is used to capture some 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.

[0071] The kiln head waste heat utilization method of this application is to discharge the gas discharged from the coal mill dust collector 10 through the coal mill exhaust fan 11 and further discharge it to the grate cooler manifold 37 for recycling. In this application, the gas discharged from the coal mill circulating air unit to the grate cooler manifold 37 is referred to as the coal mill circulating air flow; the coal mill circulating air flow will carry moisture mixed with the coal powder to form wet coal powder.

[0072] 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, first, the coal powder carried by the airflow will be dried, causing the water to evaporate. The evaporation of the water can absorb a large amount of heat, thereby improving the cooling effect of the clinker. As the airflow flows in the grate cooler 2, the coal powder also continues to rise. 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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;

[0077] 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.

[0078] In the embodiment of the present application, the step of utilizing the first wind circulation unit for waste heat power generation to circulate a portion of the flue gas entering the waste heat boiler 6 through the first wind circulation unit for waste heat power generation into the grate cooler manifold 37 for recycling includes:

[0079] Part of the flue gas entering the waste heat boiler 6 enters the kiln head dust collector 7 through the connecting pipe for dust collection treatment, and then enters the grate cooler wind box for recycling through the waste heat power generation air circulation valve 37-1 under the power of the kiln head exhaust fan 8.

[0080] Furthermore, the gas that enters the grate cooler manifold 37 for recycling after passing through the first waste heat power generation wind circulation 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 becomes 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.

[0081] In this embodiment of the present application, 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 bin 14, a kiln head pulverized coal bin 15, a kiln tail pulverized coal scale 16, a kiln head pulverized coal scale 17, a pulverized coal conveying manifold 38, a kiln tail pulverized coal blower 20, a pulverized coal standby blower 21, a kiln head pulverized coal blower 22, a kiln head burner 19, and connecting pipes.

[0082] 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.

[0083] 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.

[0084] 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 .

[0085] 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.

[0086] 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.

[0087] In the kiln head waste heat utilization method of the present application, the steps of the second wind subcirculation unit for waste heat power generation causing a portion of the flue gas entering the waste heat boiler 6 to enter the pulverized coal conveying unit through the second wind subcirculation unit for waste heat power generation, and then enter the rotary kiln 1 and the decomposition furnace 18 along with the pulverized coal, respectively, include:

[0088] The flue gas passing through the kiln head dust collector 7 passes through the kiln head exhaust fan 8 under the power of the kiln head exhaust fan 8; the pulverized coal conveying air inlet valve 38-2 enters the pulverized coal conveying wind box 38 for recycling;

[0089] The outside air is allowed to enter the pulverized coal conveying wind box 38 through the air intake valve 38-1 for circulation;

[0090] A portion of the gas in the pulverized coal transporting wind box 38 is transported to the decomposition furnace 18 through the pulverized coal scale 16 under the power of the pulverized coal blower 20 at the kiln tail;

[0091] A portion of the gas in the pulverized coal transport wind box 38 is transported to the kiln head burner 19 through the kiln head pulverized coal scale 17 under the power of the kiln head pulverized coal blower 22 .

[0092] Specifically, the kiln head exhaust fan 8 discharges part of the flue gas entering the waste heat boiler 6 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 discharges it. The discharged gas is called the coal powder conveying airflow; part of the airflow in 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.

[0093] 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.

[0094] Furthermore, the third wind sub-circulation unit for surplus wind power generation 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 surplus wind power generation 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 through the connecting pipe, and the other end is connected to the primary air inlet of the kiln head burner 19 through the connecting pipe.

[0095] In the kiln head waste heat utilization method of the present application, the steps of the third wind subcirculation unit for waste heat power generation allowing a portion of the flue gas entering the waste heat boiler 6 to enter the kiln head burner 19 as primary air through the third wind subcirculation unit for waste heat power generation include:

[0096] The flue gas passing through the kiln head dust collector 7 is transported to the kiln head primary fans 23 and 24 through connecting pipes under the power of the kiln head exhaust fan 8; and then is transported to the primary air inlet of the kiln head burner 19 through connecting pipes under the power of the kiln head primary fans 23 and 24.

[0097] In the present application, two kiln head primary fans 23 and 24 are provided, and the two kiln head primary fans 23 and 24 are provided as "one in use and one in reserve". During operation, only one of the kiln head primary fans 23 is started. When the working kiln head primary fan 23 fails, the other reserve kiln head primary fan 24 can be started.

[0098] In an embodiment of the present application, the air exhaust system for waste heat power generation is configured to discharge a portion of the flue gas entering the waste heat boiler. The air exhaust system for waste heat power generation includes a kiln head chimney 9 and connecting pipes. The kiln head chimney 9 is connected to the kiln head exhaust fan 8 through connecting pipes.

[0099] In the kiln head waste heat utilization method of the present application, the step of discharging a portion of the flue gas entering the waste heat boiler through the waste heat power generation air exhaust system includes:

[0100] The remaining flue gas after being distributed by the first wind sub-circulation unit for waste heat power generation, the second wind sub-circulation unit for waste heat power generation and the third wind sub-circulation unit for waste heat power generation is transported to the kiln head chimney 9 through the kiln head exhaust fan 8 and connecting pipes for external discharge.

[0101] Therefore, in summary, the airflow direction in the kiln head waste heat utilization system of this application is as follows:

[0102] 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.

[0103] In this embodiment of the present application, the kiln head waste heat utilization system also includes a clinker conveying unit, which includes a clinker conveyor 3, a clinker silo 4, and connecting pipes. In this application, the clinker flows as follows: After processing 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 lowering its 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, depending 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 transported to the clinker silo 4 by the clinker conveyor 3.

[0104] 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.

[0105] In an embodiment of the present application, the clinker conveyor 3 transports the clinker to the clinker storage 4 for storage after the clinker leaves the low-temperature section of the grate cooler 2. The connecting pipe in the clinker conveying unit is arranged above the clinker conveyor 3 and is connected to the connecting pipe at the outlet of the waste heat boiler 6. Specifically, a dust collecting hood is provided above the clinker conveyor 3. The dust collecting hood is located near the outlet of the grate cooler 2 and is connected to the connecting pipe above the clinker conveyor 3. 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 to merge with the gas, 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 recycled heat.

[0106] 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 method for utilizing waste heat from a kiln head, characterized in that: A kiln head waste heat utilization system is used, which includes a rotary kiln, a grate cooler, a coal mill system, a waste heat boiler, a pulverized coal conveying unit, a grate cooler wind box, a coal mill circulation air unit and a waste heat power generation air circulation unit. The outlet of the grate cooler wind box is connected to the inlet of the medium temperature section of the grate cooler. The medium temperature section is connected to the coal mill system and the waste heat boiler respectively by opening an outlet. The coal mill circulation air unit is connected between the coal mill system and the grate cooler wind box. The waste heat power generation air circulation unit includes at least a first waste heat power generation wind sub-circulation unit connected between the waste heat boiler and the grate cooler wind box. The kiln head waste heat utilization system eliminates the coal mill exhaust gas discharge coal mill chimney; The kiln head waste heat utilization method comprises the following steps: The coal mill circulating air unit is used to pass the flue gas entering the coal mill system through the coal mill circulating air unit and then enter the grate cooler wind box for recycling; A portion of the flue gas entering the waste heat boiler is fed into the grate cooler wind box through the first wind circulation unit for waste heat power generation for recycling.

2. The kiln head waste heat utilization method according to claim 1, characterized in that: The coal mill circulation 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. The steps of using the coal mill circulating air unit to pass the flue gas entering the coal mill system through the coal mill circulating air unit and then enter the grate cooler wind box for recycling include: The flue gas entering the coal mill system enters the coal mill dust collector through the connecting pipe for dust collection treatment; The flue gas passing through the coal mill dust collector enters the grate cooler wind box for recycling through the coal mill air circulation valve under the power of the coal mill exhaust fan.

3. The kiln head waste heat utilization method according to claim 2, characterized in that: The flue gas treated by the coal mill system contains a certain amount of moisture and coal powder; Filtering part of the coal powder in the flue gas by using the coal mill dust collector; The coal powder and moisture not filtered by the coal powder dust collector enter the grate cooler wind box after passing through the coal mill exhaust fan, coal mill air circulation valve and corresponding connecting pipes, and then enter the medium temperature section of the grate cooler for recycling.

4. The kiln head waste heat utilization method 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 kiln head waste heat utilization method further comprises the following steps: Using the second wind circulation unit for waste heat power generation, a portion of the flue gas entering the waste heat boiler enters the pulverized coal conveying unit through the second wind circulation unit for waste heat power generation, and then enters the rotary kiln and the decomposition furnace along with the pulverized coal; The third wind subcirculation unit for waste heat power generation is used to allow part of the flue gas entering the waste heat boiler to enter the kiln head burner through the third wind subcirculation unit for waste heat power generation and be used as primary air.

5. The kiln head waste heat utilization method according to claim 4, characterized in that: The first wind subcirculation unit for waste heat power generation 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 wind box through the connecting pipes. The step of using the first wind circulation unit for waste heat power generation to circulate a portion of the flue gas entering the waste heat boiler through the first wind circulation unit for waste heat power generation into the grate cooler wind manifold for use includes: Part of the flue gas entering the waste heat boiler enters the kiln head dust collector through the connecting pipe for dust collection treatment, and then enters the grate cooler wind box for recycling through the air circulation valve for waste heat power generation under the power of the kiln head exhaust fan.

6. The kiln head waste heat utilization method according to claim 5, characterized in that: The second wind subcirculation unit for surplus wind power generation includes an air intake valve, a pulverized coal conveying intake valve, a pulverized coal conveying wind box, a kiln tail pulverized coal blower, a kiln head pulverized coal blower and connecting pipe fittings. The air intake valve is connected to the inlet of the pulverized coal conveying wind box, one end of the pulverized coal 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 pulverized coal conveying wind box, one end of the kiln tail pulverized coal blower is connected to the outlet of the pulverized coal conveying wind box through a connecting pipe fitting, and the other end is connected to the decomposition furnace through a kiln tail pulverized coal scale through a connecting pipe fitting, and one end of the kiln head pulverized coal blower is connected to the outlet of the pulverized coal 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 pulverized coal scale; The steps of the second wind subcirculation unit for waste heat power generation causing a portion of the flue gas entering the waste heat boiler to enter the pulverized coal conveying unit through the second wind subcirculation unit for waste heat power generation, and then respectively entering the rotary kiln and the decomposition furnace along with the pulverized coal include: The flue gas passing through the kiln head dust collector enters the coal powder conveying wind box through the coal powder conveying air inlet valve under the power of the kiln head exhaust fan for recycling; The outside air is allowed to enter the coal powder conveying wind box for circulation through the air intake valve; A portion of the gas in the coal powder transport wind box is transported to the decomposition furnace through the coal powder scale at the kiln tail under the power of the coal powder blower at the kiln tail; A portion of the gas in the coal powder transport wind box is transported to the kiln head burner through the kiln head coal powder scale under the power of the kiln head coal powder blower.

7. The kiln head waste heat utilization method according to claim 5 or 6, characterized in that: The third wind subcirculation unit for surplus wind power generation includes a kiln head primary fan and a connecting pipe fitting, one end of the kiln head primary fan is connected to the outlet of the kiln head exhaust fan through the connecting pipe fitting, and the other end is connected to the primary air inlet of the kiln head burner through the connecting pipe fitting; The steps of the third wind subcirculation unit for waste heat power generation transferring a portion of the flue gas entering the waste heat boiler into the kiln head burner as primary air through the third wind subcirculation unit for waste heat power generation include: The flue gas passing through the kiln head dust collector is transported to the kiln head primary fan through the connecting pipe under the power of the kiln head exhaust fan; and then transported to the primary air inlet of the kiln head burner through the connecting pipe under the power of the kiln head primary fan.

8. The kiln head waste heat utilization method according to claim 7, characterized in that: The kiln head waste heat utilization system also includes a waste heat power generation air exhaust system, which is configured to exhaust a portion of the flue gas entering the waste heat boiler through the waste heat power generation air exhaust system; the waste heat power generation air exhaust system 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 step of discharging a portion of the flue gas entering the waste heat boiler through the waste heat power generation air exhaust system includes: The remaining flue gas distributed by the first wind sub-circulation unit for waste heat power generation, the second wind sub-circulation unit for waste heat power generation and the third wind sub-circulation unit for waste heat power generation is transported to the kiln head chimney through the connecting pipe to be discharged externally.

9. The kiln head waste heat utilization method according to claim 7, characterized in that: An outlet is opened in the low-temperature section of the grate cooler, and the outlet of the grate cooler is connected to the outlet of the waste heat boiler through a connecting pipe; The low-temperature flue gas discharged from the low-temperature section enters the connecting pipe of the waste heat boiler outlet through the connecting pipe fitting and merges with the flue gas passing through the waste heat boiler and then enters the kiln head dust collector together.

10. The kiln head waste heat utilization method according to claim 9, characterized in that: The kiln head waste heat utilization system further includes a clinker conveying unit; the clinker conveying unit includes a clinker storage for storing clinker, a clinker conveyor for transporting clinker from the grate cooler to the clinker storage, and a connecting pipe located above the clinker conveyor, wherein the connecting pipe located above the clinker conveyor is connected to the connecting pipe located at the outlet of the waste heat boiler; The heat emitted by the clinker conveyor when conveying clinker is recovered by utilizing the connecting pipe above the clinker conveyor; The step of recovering the heat emitted by the clinker conveyor when conveying clinker by utilizing the connecting pipe above the clinker conveyor comprises: After the clinker in the grate cooler exchanges heat with the gas, the clinker falls to the clinker conveyor; The heat emitted by the clinker on the clinker conveyor is combined with the flue gas passing through the waste heat boiler through the connecting pipe and then enters the kiln head dust collector together.

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