A method for reducing NO in cement clinker calcination systems x device

Abstract

The utility model discloses a kind of devices for reducing cement clinker firing system NO x It relates to cement production equipment technical field, and the cement clinker firing system includes preheater, decomposing furnace, rotary kiln and grate cooler connected in turn, the device includes: flue gas shunting component, for extracting system high-temperature flue gas;Flue gas re-injection component, its inlet is connected with the outlet of the flue gas shunting component, and its outlet end is equipped with one or more spray guns, the injection port of the spray gun is arranged in the kiln tail smoke chamber of the rotary kiln and / or the lower cone area of the decomposing furnace;Control component is signal connected with the flue gas shunting component, for adjusting the gas volume and / or temperature of shunting flue gas in real time according to the operating state of the cement clinker firing system.This device does not need additional reducing agent, by constructing reducing atmosphere, NO x It is reduced to N2, and the operation cost is low, control is accurate, adapts existing system modification, does not affect cement clinker production quality, and safety is high.

Description

Technical Field

[0001] This utility model relates to the technical field of cement production equipment, and more specifically to a method for reducing NO in cement clinker calcination systems. x The device. Background Technology

[0002] In cement production, the cement clinker calcination system is the core process unit, typically consisting of a preheater, a preheater, a rotary kiln, and a grate cooler connected in sequence. The preheater, along the flue gas flow direction, is further divided into multiple stages (e.g., five stages) for preheating the raw materials. However, during operation, the high-temperature combustion in the rotary kiln and the fuel decomposition reaction in the preheater generate large amounts of NO. x Direct emissions would cause serious air pollution and would not comply with current environmental regulations. Existing systems for reducing NO2 in cement clinker calcination x The main emission reduction technologies include low-NOx burner retrofitting, selective non-catalytic reduction (SNCR) technology, and selective catalytic reduction (SCR) technology. Among these, low-NOx burner retrofitting can only reduce NOx emissions to a limited extent by optimizing combustion conditions. x The current generation and emission reduction effects of SNCR technology are relatively limited. SNCR technology requires the injection of reducing agents such as ammonia and urea into the system, which not only increases raw material costs but may also cause ammonia escape and secondary pollution due to uneven injection of reducing agents. Although SCR technology has high emission reduction efficiency, it requires a dedicated catalytic reaction device, resulting in extremely high investment and operation and maintenance costs, making it difficult to widely apply in small and medium-sized cement production lines. Therefore, there is an urgent need for a NO reduction method that is simple in structure, low in cost, has stable emission reduction effects, and is compatible with existing calcination systems. x Lowering device. Utility Model Content

[0003] The purpose of this invention is to solve the NO problem in existing cement clinker calcination systems. x Existing emission reduction technologies suffer from limitations in emission reduction effects, high costs, and the potential for secondary pollution. This invention addresses these issues by providing a method for reducing NOx emissions in cement clinker calcination systems. x The device.

[0004] The technical solution adopted in this utility model is as follows: A method for reducing NO in cement clinker calcination systems. x The apparatus, wherein the cement clinker calcination system comprises a preheater, a decomposition furnace, a rotary kiln, and a grate cooler connected in sequence, includes: A flue gas diversion assembly, the diversion inlet of which is connected to the outlet pipe of the preheater or the decomposition furnace, is used to extract a portion of the high-temperature flue gas. The flue gas re-injection assembly has its inlet connected to the outlet of the flue gas diversion assembly, and its outlet is equipped with a spray gun. The spray nozzle of the spray gun is arranged in the kiln tail flue chamber of the rotary kiln and / or the conical region of the decomposition furnace. A control component, signal-connected to the flue gas diversion component, is used to adjust the diverted flue gas according to the operating status of the cement clinker calcination system. Preferably, the flue gas diversion assembly includes a diversion pipe, an induced draft fan, and a first control valve; the control assembly is signal-connected to the induced draft fan and / or the first control valve to adjust the flue gas diversion rate. Preferably, the control component includes a temperature sensor and a controller; the temperature sensor is used to detect the temperature of the diverted flue gas in real time; the controller adjusts the opening of the first control valve according to the temperature signal detected by the temperature sensor to control the temperature of the re-injected flue gas.

[0005] Preferably, the control component further includes a gas analyzer for monitoring NO in the flue gas. x Concentration; the controller also adjusts the NO concentration based on the gas analyzer's detection. x The concentration signal is used to adjust the operating parameters of the induced draft fan. Preferably, the spray gun is tilted and its spray direction is directed towards the kiln tail flue chamber of the rotary kiln or the central area of ​​the decomposition furnace. Preferably, the spray gun is equipped with an ignition and stabilization device for igniting the diverted flue gas to maintain a reducing atmosphere. Preferably, the diversion inlet of the flue gas diversion assembly is connected to the outlet pipe of the second-stage preheater (C4) of the preheater. Preferably, it further includes a cooling air bypass system, which includes a bypass pipe and a second control valve; one end of the bypass pipe is connected to the cooling air recovery pipe of the high-temperature cooling air area of ​​the grate cooler, and the other end is connected to the pipe of the flue gas re-injection assembly; the second control valve is signal-connected to the control assembly and is used to adjust the temperature of the re-injected flue gas. Preferably, the connection point of the bypass pipe of the cooling air bypass system to the flue gas re-injection component pipe is located downstream of the induced draft fan of the flue gas diversion component. Preferably, the outer wall of the flue gas re-injection assembly is covered with a layer of fire-resistant and heat-insulating material.

[0006] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are: 1. High-efficiency and low-cost emission reduction: This invention ingeniously extracts the medium-temperature flue gas containing reducing components such as CO and N2 generated by the system itself and then re-injects it into the NO2 system. xThe kiln tail flue chamber and the lower area of ​​the decomposition furnace, where the highest concentrations of NO are present, create a localized strong reducing atmosphere, efficiently reducing NO without consuming external chemical reducing agents (such as ammonia). x Reducing to N2 significantly lowers NO levels. x The operating costs of emissions reduction.

[0007] 2. Strong system adaptability: By setting control components, the system can adapt to the NO signal at the system output. x The concentration and temperature of the diverted flue gas are intelligently adjusted in real time to regulate the volume and temperature of the re-injected flue gas, ensuring that the reduction reaction always takes place under optimal conditions, adapting to fluctuations in cement production conditions, and achieving stable and efficient denitrification.

[0008] 3. Safety, reliability and energy saving: The spray gun is equipped with an ignition and combustion stabilization device to ensure the continuous progress of the reduction reaction when the flue gas temperature is low; a cooling air bypass system is added to flexibly adjust the temperature of the re-sprayed flue gas and prevent the spray gun and kiln lining from being damaged due to overheating; the pipes are covered with heat insulation material to reduce heat loss and improve the system thermal efficiency.

[0009] 4. No secondary pollution: It fully utilizes the waste gas components in the process, avoiding the ammonia escape problem that may be caused by SNCR technology, making it more environmentally friendly. Attached Figure Description

[0010] This utility model will be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a connection block diagram of the control component of this utility model; The diagram is labeled as follows: 1-Preheater, C1-Fifth stage preheater, C2-Fourth stage preheater, C3-Third stage preheater, C4-Second stage preheater, C5-First stage preheater, 2-Decomposition furnace, 22-Gas analyzer, 3-Rotary kiln, 4-Grate cooler, 41-Cooling air recovery pipe, 42-Bypass pipe, 43-Second control valve, 5-Flue gas diversion assembly, 51-Diversion pipe, 52-Induced draft fan, 53-First control valve, 54-Temperature sensor, 6-Spray gun, 61-Ignition stabilizer, 7-Control assembly, 71-Controller. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can typically be arranged and designed in various different configurations.

[0012] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0013] In one embodiment of this utility model, such as Figure 1-2 As shown, this embodiment provides a method for reducing NO in a cement clinker calcination system. x The apparatus, wherein the cement clinker calcination system comprises a preheater 1, a decomposition furnace 2, a rotary kiln 3, and a grate cooler 4 connected in sequence, wherein the preheater 1 comprises a first-stage preheater C1 to a fifth-stage preheater C5 arranged sequentially along the flue gas flow direction. The apparatus includes: The flue gas diversion assembly 5 has its diversion inlet connected to the outlet pipe of the third-stage preheater C3 cyclone, the outlet pipe of the second-stage preheater C4 cyclone, or the outlet pipe of the decomposition furnace 2, for extracting a portion of the high-temperature flue gas from the cement clinker calcination system. The flue gas re-injection assembly has its inlet connected to the outlet of the flue gas diversion assembly 5, and its outlet end is provided with one or more spray guns 6. The spray nozzles of the spray guns 6 are arranged in the kiln tail flue chamber of the rotary kiln 3 and / or the lower conical region of the decomposition furnace 2. The control component 7 is signal-connected to the flue gas diversion component 5 and is used to adjust the flow rate and / or temperature of the diverted flue gas in real time according to the operating status of the cement clinker calcination system.

[0014] In another embodiment of the present invention, the flue gas diversion assembly 5 includes a diversion pipe 51, an induced draft fan 52 disposed on the diversion pipe 51, and a first control valve 53; the control assembly 7 is signal-connected to the induced draft fan 52 and / or the first control valve 53.

[0015] In another embodiment of the present invention, the control component 7 includes a temperature sensor 54 and a controller 71; the temperature sensor 54 is disposed in the diversion pipe 51 or at the inlet of the spray gun 6; the controller 71 adjusts the opening degree of the first control valve 53 according to the temperature signal detected by the temperature sensor 54.

[0016] In another embodiment of this utility model, the control component 7 further includes a gas analyzer 22, which is disposed at the outlet of the decomposition furnace 2 or the outlet flue of the first-stage preheater C5; the controller 71 further analyzes the NO detected by the gas analyzer 22. x The concentration signal dynamically adjusts the operating frequency of the induced draft fan 52.

[0017] In another embodiment of this utility model, there are multiple spray guns 6, which are evenly arranged along the circumference of the kiln tail flue chamber of the rotary kiln 3 or the circumference of the lower cone of the decomposition furnace 2; the spraying direction of the spray guns 6 is inclined downward, forming an angle of 30°–60° with the horizontal direction.

[0018] In another embodiment of this utility model, an ignition and combustion stabilization device is provided at the nozzle of the spray gun 6.

[0019] In another embodiment of the present invention, the diversion inlet of the flue gas diversion component 5 is preferably connected to the outlet pipe of the second-stage preheater C4 cyclone of the preheater 1.

[0020] In another embodiment of the present invention, a cooling air bypass system is also included, the cooling air bypass system including a bypass pipe 42 and a second control valve 43; one end of the bypass pipe 42 is connected to the high-temperature cooling air recovery pipe 41 of the grate cooler 4, and the other end is connected to the pipe of the flue gas re-injection assembly; the second control valve 43 is signal connected to the control assembly 7.

[0021] In another embodiment of this utility model, the bypass pipe 42 of the cooling air bypass system is located downstream of the induced draft fan 52 of the flue gas diversion assembly 5.

[0022] In another embodiment of this utility model, the outer wall of the flue gas re-injection assembly is covered with a layer of fire-resistant and heat-insulating material.

[0023] Specifically, a method to reduce NO in cement clinker calcination systems x The device itself includes a preheater 1 (composed of five cyclone preheaters from C5 to C1), a decomposition furnace 2, a rotary kiln 3, and a grate cooler 4, which are connected in sequence by pipes.

[0024] The device of this utility model mainly includes a flue gas diversion component 5, a flue gas re-injection component, and a control component 7.

[0025] The diversion inlet of the flue gas diversion assembly 5 is connected to the outlet pipe of the cyclone separator of the second-stage preheater C4. This location offers a suitable flue gas temperature (typically around 800-900℃) and contains a high concentration of reducing gases such as CO, making it an ideal location for extracting the diverted flue gas. Alternatively, depending on the actual operating conditions, the diversion inlet can also be connected to the outlet pipe of the third-stage preheater C3 or the decomposition furnace 2. The flue gas diversion assembly 5 includes a diversion pipe 51, an induced draft fan 52, and a first control valve 53. The induced draft fan 52 provides power to extract the high-temperature flue gas from the main process pipe, and the first control valve 53 is used to precisely regulate the flow rate of the diverted flue gas.

[0026] The inlet of the flue gas re-injection assembly is connected to the outlet of the diversion pipe 51, and multiple spray guns 6 are connected to its end. These spray guns 6 are preferably arranged in the kiln tail flue chamber of the rotary kiln 3, but can also be arranged in the lower conical region of the decomposition furnace 2, or both. The spray guns 6 are evenly distributed around the circumference of the kiln tail flue chamber, and their spray direction is inclined downward at an angle of about 45° to the horizontal direction, pointing towards the central area of ​​the kiln tail flue chamber, to ensure that the reducing flue gas and the kiln tail flue gas are fully and uniformly mixed.

[0027] The control component 7 is the core of this invention for achieving intelligent control. It includes a temperature sensor 54 installed on the diversion pipe 51 and a gas analyzer 22 installed on the flue gas duct at the outlet of the first-stage preheater C5 (for monitoring NO). x (and O2 concentration) and controller 71 (such as a PLC or DCS system). Controller 71 receives signals from temperature sensor 54 and gas analyzer 22.

[0028] When the temperature of the diverted flue gas is detected to be too high, the controller 71 can increase the opening of the first control valve 53 to increase the flue gas flow to cool it down, or start the cooling air bypass system described later.

[0029] When gas analyzer 22 detects NO at the outlet x When the concentration increases, the controller 71 will increase the operating frequency of the induced draft fan 52 to increase the total amount of re-injected reducing flue gas and enhance the reduction effect; conversely, it will reduce the frequency to achieve emission reduction on demand.

[0030] In a preferred embodiment, the nozzle of the spray gun 6 is equipped with an ignition and flame stabilization device 61 (such as a high-energy igniter). When the temperature of the diverted flue gas is low or the concentration of its combustible components fluctuates, causing the reduction reaction to weaken, the ignition and flame stabilization device 61 can be activated to ignite the combustible components in the flue gas, maintain the flame and high-temperature reducing atmosphere at the nozzle, and ensure denitrification efficiency.

[0031] In another preferred embodiment, a cooling air bypass system is also provided. It includes a bypass pipe 42 and a second control valve 43. One end of the bypass pipe 42 is connected to the cooling air recovery pipe 41 of the high-temperature section of the grate cooler 4, and the other end is connected to the flue gas re-injection pipe downstream of the induced draft fan 52. The controller 71 can adjust the opening of the second control valve 43 according to the signal from the temperature sensor 54, mixing in an appropriate amount of low-temperature cooling air, thereby quickly and accurately controlling the temperature of the re-injected flue gas within the optimal range, ensuring both efficient reduction reaction and equipment safety.

[0032] In addition, the outer walls of all pipes of the flue gas re-injection assembly are covered with a layer of refractory and heat-insulating material (not shown in the figure) to reduce heat loss of flue gas during transportation and maintain its activity.

[0033] Working principle: During operation of the cement kiln system, the induced draft fan 52 draws high-temperature flue gas rich in reducing components from the outlet of the second-stage preheater C4. This flue gas is transported through the diversion pipe 51, and after the gas volume and temperature are adjusted by the control component 7, it is injected at high speed into the high-temperature, high-NOx gas chamber at the kiln tail through the spray gun 6. x In this area, the injected reducing flue gas (CO, H2, etc.) mixes intensely with the flue gas, resulting in the following chemical reaction: CO + NO → CO2 + 1 / 2 N2, thereby reducing NO... x It is restored to harmless N2. The entire process utilizes the system's own "waste," achieving the goal of treating waste with waste and achieving low-cost, high-efficiency denitrification.

[0034] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural transformations made based on the concept of this utility model and the contents of the specification and drawings of this utility model, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this utility model.

Claims

1. A method for reducing NO in cement clinker calcination systems x The apparatus, wherein the cement clinker calcination system comprises a preheater (1), a decomposition furnace (2), a rotary kiln (3), and a grate cooler (4) connected in sequence, is characterized in that, include: The flue gas diversion assembly (5) has its diversion inlet connected to the outlet pipe of the preheater (1) or the decomposition furnace (2) for extracting part of the high-temperature flue gas. The flue gas re-injection assembly has its inlet connected to the outlet of the flue gas diversion assembly (5), and its outlet end is provided with a spray gun (6). The spray nozzle of the spray gun (6) is arranged in the kiln tail smoke chamber of the rotary kiln (3) and / or the conical area of ​​the decomposition furnace (2). The control component (7) is signal-connected to the flue gas diversion component (5) and is used to adjust the diverted flue gas according to the operating status of the cement clinker calcination system.

2. The apparatus according to claim 1, characterized in that, The flue gas diversion assembly (5) includes a diversion pipe (51), an induced draft fan (52), and a first control valve (53); the control assembly (7) is signal-connected to the induced draft fan (52) and / or the first control valve (53) to adjust the flue gas diversion rate.

3. The apparatus according to claim 2, characterized in that, The control component (7) includes a temperature sensor (54) and a controller (71); the temperature sensor (54) is used to detect the temperature of the diverted flue gas in real time; the controller (71) adjusts the opening of the first control valve (53) according to the temperature signal detected by the temperature sensor (54) to control the temperature of the re-injected flue gas.

4. The apparatus according to claim 3, characterized in that, The control component (7) also includes a gas analyzer (22) for monitoring NO in the flue gas. x Concentration; the controller (71) also measures the NO concentration detected by the gas analyzer (22). x The concentration signal adjusts the operating parameters of the induced draft fan (52).

5. The apparatus according to claim 1, characterized in that, The spray gun (6) is tilted and its spray direction is directed towards the kiln tail flue of the rotary kiln (3) or the central area of ​​the decomposition furnace (2).

6. The apparatus according to claim 5, characterized in that, The spray gun (6) is equipped with an ignition and stabilization device (61) for igniting the diverted flue gas to maintain a reducing atmosphere.

7. The apparatus according to claim 1, characterized in that, The diversion inlet of the flue gas diversion assembly (5) is connected to the outlet pipe of the second-stage preheater (C4) of the preheater (1).

8. The apparatus according to claim 1, characterized in that, It also includes a cooling air bypass system, which includes a bypass pipe (42) and a second control valve (43); one end of the bypass pipe (42) is connected to the cooling air recovery pipe (41) of the high temperature cooling air area of ​​the grate cooler (4), and the other end is connected to the pipe of the flue gas re-injection assembly; the second control valve (43) is signal-connected to the control assembly (7) and is used to adjust the temperature of the re-injected flue gas.

9. The apparatus according to claim 8, characterized in that, The bypass pipe (42) of the cooling air bypass system is connected to the flue gas re-injection component pipe at a point downstream of the induced draft fan (52) of the flue gas diversion component (5).

10. The apparatus according to any one of claims 1–9, characterized in that, The outer wall of the flue gas re-injection assembly's pipe is covered with a layer of fire-resistant and heat-insulating material.

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