A fuel preheating combustion system

Abstract

This invention discloses a fuel preheating and combustion system. The system includes a feeding device for conveying fuel; a preheating furnace connected to the feeding device for preheating the fuel; a combustion furnace connected to the preheating furnace for receiving and burning the fuel output from the preheating furnace; a boiler connected to the flue gas outlet of the combustion furnace; and a multi-stage air distribution device. The multi-stage air distribution device includes an air preheater connected to the flue gas outlet of the boiler and capable of air circulation, and multiple air distribution pipes connecting the air preheater to the combustion furnace. These multiple air distribution pipes are evenly distributed along the length of the combustion furnace, and each air distribution pipe is equipped with an air path control valve. The fuel preheating and combustion system provided by this invention not only enables large-scale consumption of low-volatile, low-calorific-value fuels but also achieves the recycling of high-temperature flue gas energy, saving energy and reducing environmental pollution. Furthermore, the multi-stage air distribution device achieves low NOx emissions. X combustion.

Description

Technical Field

[0001] This invention relates to the field of fuel combustion technology, and in particular to a fuel preheating combustion system. Background Technology

[0002] The gasification slag produced by coal gasification process has a large loss on ignition and does not meet the standards for building admixture raw materials, making it difficult to use directly in building and road projects. This results in a lack of effective large-scale disposal methods for gasification slag. The large-scale generation of gasification slag causes serious waste of resources, occupies a large amount of land resources, causes air pollution due to dust, and causes soil and water pollution due to leachate after long-term stockpiling or landfilling.

[0003] In existing technologies, coal-based low-volatile matter and low-calorific-value fuels are typically recycled by blending them in a low proportion before combustion in a boiler; alternatively, carbon powder obtained through flotation decarbonization can be directly used as fuel in combustion equipment. However, when using low-proportion blending, the high moisture content of some coal-based low-volatile matter and low-calorific-value fuels and the large volume requiring processing can reduce the stability of the boiler system and negatively impact combustion efficiency, hindering the large-scale utilization of these fuels. Flotation decarbonization, compared to direct blending, increases the blending ratio and optimizes the blending process. The resulting ash powder can be used in building materials and road and bridge engineering, achieving graded and high-value utilization of coal-based low-volatile matter and low-calorific-value fuels. However, the high costs associated with equipment, reagents, and labor in the flotation process make it difficult to achieve large-scale utilization of coal-based low-volatile matter and low-calorific-value fuels using flotation decarbonization.

[0004] Therefore, how to achieve large-scale consumption of fuels with low volatile matter and low calorific value is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a fuel preheating combustion system to achieve large-scale consumption of fuels with low volatile matter and low calorific value.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A fuel preheating combustion system, comprising:

[0008] A conveying device used to transport fuel;

[0009] A preheating furnace connected to the conveying device is used to preheat the fuel;

[0010] A combustion furnace connected to the preheating furnace is used to receive and burn the fuel output from the preheating furnace;

[0011] A boiler connected to the flue gas outlet of the combustion furnace, the boiler being provided with a cavity for holding a liquid medium;

[0012] A multi-stage air distribution device, comprising an air preheater connected to the flue gas outlet of the boiler and capable of communicating with air, and multiple air distribution pipelines connecting the air preheater to the combustion furnace. The multiple air distribution pipelines are evenly distributed along the length of the combustion furnace, and each air distribution pipeline is equipped with an air path control valve.

[0013] Preferably, in the above-mentioned fuel preheating combustion system, the flue gas outlet of the air preheater is connected to the preheating furnace.

[0014] Preferably, the above-mentioned fuel preheating and combustion system further includes a central controller, an outlet fuel temperature controller installed in the preheating furnace, and a flow-through temperature controller installed in the combustion furnace. The outlet fuel temperature controller, the flow-through temperature controller, and the multi-stage air distribution device are all electrically connected to the central controller.

[0015] Preferably, the above-mentioned fuel preheating combustion system further includes an online flue gas monitoring device located at the end of the combustion furnace, and both the online flue gas monitoring device and the material conveying device are electrically connected to the central controller.

[0016] Preferably, the above-mentioned fuel preheating combustion system further includes an outlet flue gas pipeline connected to the preheating furnace, an induced draft fan installed in the outlet flue gas pipeline, and a chimney connected to the outlet flue gas pipeline.

[0017] Preferably, the above-mentioned fuel preheating combustion system further includes a flue gas recirculation pipeline, which connects the outlet flue gas pipeline and the air preheater, and the flue gas recirculation pipeline is equipped with an opening control valve.

[0018] Preferably, in the above-described fuel preheating combustion system, the multi-stage air distribution device further includes a blower for supplying air to the air preheater.

[0019] Preferably, in the above-mentioned fuel preheating combustion system, the combustion furnace is a rotary kiln structure inclined to the horizontal plane, and the end of the combustion furnace closer to the preheating furnace is higher than the end of the combustion furnace farther from the preheating furnace.

[0020] Preferably, in the above-mentioned fuel preheating combustion system, the preheating furnace is a horizontally arranged rotary kiln structure, and the inner wall of the preheating furnace is provided with inner spiral blades and baffles connecting the inner spiral blades.

[0021] Preferably, in the above-mentioned fuel preheating combustion system, there are three air distribution pipes, namely a first air distribution pipe, a second air distribution pipe, and a third air distribution pipe. The first air distribution pipe is equipped with a primary air distribution valve, the second air distribution pipe is equipped with a secondary air distribution valve, and the third air distribution pipe is equipped with a tertiary air distribution valve.

[0022] When using the fuel preheating and combustion system provided by this invention, low-volatile, low-calorific-value fuel is fed into the preheating furnace via a feeding device. The preheating furnace preheats the fuel, allowing it to fully combust, thus achieving large-scale utilization of the fuel. Because the boiler and the combustion furnace have their flue gas outlets connected, the ultra-high-temperature flue gas discharged from the combustion furnace exchanges heat with the liquid medium in the boiler, generating high-temperature steam and achieving energy output. This utilizes the waste heat of the ultra-high-temperature flue gas, saving energy and reducing environmental pollution. Furthermore, because the air preheater of the multi-stage distribution device is connected to the boiler's flue gas outlet and can be exposed to air, multiple air distribution ducts connect the air preheater to the combustion furnace. Therefore, when the air preheater is connected to the air supply, the high-temperature flue gas discharged from the boiler's flue gas outlet enters the air preheater, preheating the air in the preheater. The preheated air then enters the combustion furnace through multiple air distribution ducts, further realizing the recycling of high-temperature flue gas, saving energy, and reducing pollution. Since the multiple air distribution ducts are evenly distributed along the length of the combustion furnace, the preheated air can be distributed to the furnace along its length, achieving multi-stage air distribution. Each air distribution duct is equipped with an airflow control valve, allowing adjustment of the airflow in each duct. By adjusting the airflow in each duct, a reducing atmosphere is maintained in the main combustion zone at the front end of the combustion furnace, achieving low NO₂ levels. X Combustion. Therefore, the fuel preheating combustion system provided by this invention not only achieves large-scale consumption of low-volatile, low-calorific-value fuels, but also realizes the recycling of high-temperature flue gas energy, saving energy and reducing environmental pollution. Simultaneously, it achieves low NOx emissions through a multi-stage air distribution device. X combustion. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1This is a schematic diagram of the structure of a fuel preheating combustion system provided in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of another fuel preheating combustion system provided in an embodiment of the present invention.

[0026] Among them, 100 is the material conveying device, 200 is the preheating furnace, 201 is the outlet flue gas pipeline, 202 is the induced draft fan, 203 is the chimney, 300 is the combustion furnace, 400 is the boiler, 500 is the multi-stage air distribution device, 501 is the air preheater, 502 is the air distribution pipeline, 5021 is the first air distribution pipeline, 5022 is the second air distribution pipeline, 5023 is the third air distribution pipeline, 503 is the forced draft fan, 600 is the flue gas online monitoring device, and 700 is the flue gas recirculation pipeline. Detailed Implementation

[0027] In view of this, the core of the present invention is to provide a fuel preheating combustion system to achieve large-scale consumption of fuels with low volatile matter and low calorific value.

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] like Figures 1 to 2 As shown in the figure, an embodiment of the present invention discloses a fuel preheating and combustion system, including a material conveying device 100, a preheating furnace 200, a combustion furnace 300, a boiler 400, and a multi-stage air distribution device 500.

[0030] The material conveying device 100 is used to convey fuel; the preheating furnace 200 is connected to the material conveying device 100 and is used to preheat the fuel; the combustion furnace 300 is connected to the preheating furnace 200 and is used to receive and burn the fuel output by the preheating furnace 200; the boiler 400 is connected to the flue gas outlet of the combustion furnace 300 and the boiler 400 is provided with a cavity for holding liquid media; the multi-stage air distribution device 500 includes an air preheater 501 connected to the flue gas outlet of the boiler 400 and capable of conducting with air, and multiple air distribution pipes 502 connecting the air preheater 501 and the combustion furnace 300. The multiple air distribution pipes 502 are evenly distributed along the length of the combustion furnace 300, and each air distribution pipe 502 is provided with an air path control valve.

[0031] When using the fuel preheating and combustion system provided by this invention, low-volatile, low-calorific-value fuel is fed into the preheating furnace 200 via the feeding device 100. The preheating furnace 200 preheats the fuel, and then the fuel enters the combustion furnace 300 for complete combustion, achieving large-scale consumption of the fuel. Since the boiler 400 and the combustion furnace 300 are connected at their flue gas outlets, the ultra-high temperature flue gas discharged from the combustion furnace 300 exchanges heat with the liquid medium (water in this embodiment) in the boiler 400, causing the liquid medium to generate high-temperature steam and achieve energy output. This realizes the utilization of waste heat from the ultra-high temperature flue gas, saving energy and reducing environmental pollution. Furthermore, since the air preheater 501 of the multi-stage distribution device is connected to the flue gas outlet of the boiler 400 and can be connected to the air, multiple air distribution pipes 502 are connected to the air preheater 501. 1. Since the air preheater 501 is connected to the combustion furnace 300, when the air preheater 501 is connected to the air supply, the high-temperature flue gas discharged from the flue gas outlet of the boiler 400 enters the air preheater 501. The high-temperature flue gas preheats the air in the air preheater 501. The preheated air then enters the combustion furnace 300 through multiple air distribution pipes 502, further realizing the recycling of high-temperature flue gas, saving energy, and reducing pollution. Because the multiple air distribution pipes 502 are evenly distributed along the length of the combustion furnace 300, the preheated air can be distributed to the combustion furnace 300 along its length, achieving multi-stage air distribution. Since each air distribution pipe 502 is equipped with an airflow control valve, the airflow of each air distribution pipe can be adjusted. By adjusting the airflow of each air distribution pipe 502, a reducing atmosphere is maintained in the main combustion zone at the front end of the combustion furnace 300, achieving low NO₂ levels. X Combustion. Therefore, the fuel preheating combustion system provided by this invention not only achieves large-scale consumption of low-volatile, low-calorific-value fuels, but also realizes the recycling of high-temperature flue gas energy, saving energy and reducing environmental pollution. Simultaneously, it achieves low NOx emissions through a multi-stage air distribution device. X combustion.

[0032] It should be understood that the preheating furnace 200 can be directly installed below the outlet of the conveying device 100, allowing fuel to enter the preheating furnace 200 from the outlet of the conveying device 100 under its own weight. Alternatively, fuel can be transported to the preheating furnace 200 through a separately installed transmission mechanism, as long as the usage requirements are met. Similarly, the combustion furnace 300 can be directly installed below the preheating furnace 200, allowing preheated fuel to enter the combustion furnace 300 under its own weight. Alternatively, fuel can be transported to the combustion furnace 300 through a separately installed transmission mechanism, as long as the usage requirements are met. The requirements can be met; optionally, the preheating furnace 200 provided in this embodiment of the invention is directly disposed below the outlet of the conveying device 100, and a hopper is provided between the conveying device 100 and the preheating furnace 200 so that the fuel enters the preheating furnace 200 through the hopper under its own weight, reducing fuel spillage; the combustion furnace 300 is directly disposed below the preheating furnace 200, and is connected to the preheating furnace 200 and the combustion furnace 300 through corresponding pipelines so that the fuel enters the combustion furnace 300 from the preheating furnace 200 through the pipeline under its own weight, and the fuel is burned in the combustion furnace 300.

[0033] Furthermore, the flue gas outlet of the air preheater 501 is connected to the preheating furnace 200 so that the air can be fully preheated by the high-temperature flue gas in the air preheater 501. After the high-temperature flue gas that has completed the heat exchange is discharged from the flue gas outlet of the air preheater 501, it enters the preheating furnace 200 to fully preheat the fuel in the preheating furnace 200, thereby improving the utilization rate of the output calorific value of the low volatile matter and low calorific value fuel.

[0034] In addition, the fuel preheating and combustion system also includes a central controller, an outlet fuel temperature controller installed in the preheating furnace 200, and a flow temperature controller installed in the combustion furnace 300. The outlet fuel temperature controller, the flow temperature controller, and the multi-stage air distribution device 500 are all electrically connected to the central controller so that the fuel temperature at the outlet of the preheating furnace 200 can be detected by the outlet fuel temperature controller, and the flow temperature inside the combustion furnace 300 can be detected by the flow temperature controller. After receiving the fuel temperature information at the outlet of the preheating furnace 200 and the flow temperature information inside the combustion furnace 300, the central controller automatically adjusts the opening of the air path control valves of each air distribution pipe 502 of the multi-stage air distribution device 500, thereby adjusting the air volume of each air distribution pipe 502 so that the combustion furnace 300 can achieve isothermal combustion throughout the entire process.

[0035] Furthermore, the fuel preheating combustion system also includes an online flue gas monitoring device 600 located at the end of the combustion furnace 300. Both the online flue gas monitoring device 600 and the material conveying device 100 are electrically connected to the central controller, so that the online flue gas monitoring device 600 can monitor the ultra-high temperature flue gas near the outlet of the combustion furnace 300 for O2, CO, and NO. xThe system performs real-time detection of components and feeds the results back to the central controller. Based on the detection results, the fuel temperature information at the outlet of the preheating furnace 200, and the temperature information along the combustion furnace 300, the central controller adjusts the fuel input of the conveying device 100 and the air supply of the multi-stage air distribution device 500 in a timely manner. This further regulates the large-scale and stable operation of the fuel preheating and combustion system, thereby realizing the large-scale and stable consumption of coal-based low volatile matter and low calorific value fuels, the intelligent combustion of low NOx with isothermal conditions throughout the process, and the full utilization of the energy of low volatile matter and low calorific value fuels.

[0036] like Figure 1 As shown, the fuel preheating combustion system also includes an outlet flue gas pipeline 201 connected to the preheating furnace 200, an induced draft fan 202 installed in the outlet flue gas pipeline 201, and a chimney 203 connected to the outlet flue gas pipeline 201, so that the flue gas discharged from the preheating furnace 200 can enter the chimney 203 through the outlet flue gas pipeline 201 and be discharged from the chimney 203 under the action of the induced draft fan 202.

[0037] like Figure 2 As shown, in a specific embodiment of the present invention, the fuel preheating combustion system further includes a flue gas recirculation pipeline 700, which connects the outlet flue gas pipeline 201 and the air preheater 501. The flue gas recirculation pipeline 700 is equipped with an opening control valve to introduce part of the flue gas in the outlet flue gas pipeline 201 into the air preheater 501, and to control the amount of flue gas entering the air preheater 501 through the opening control valve, thereby realizing the ratio regulation of air and flue gas.

[0038] In addition, the opening control valve can be electrically connected to the central controller, so that the central controller can automatically adjust the opening of the opening control valve according to the temperature feedback along the combustion furnace 300, and further regulate the large-scale stable operation of the fuel preheating combustion system.

[0039] The multi-stage air distribution device 500 provided by the present invention also includes a blower 503 to deliver air to the air preheater 501. The opening control valve is provided at the connection between the flue gas recirculation pipeline 700 and the blower 503 to control the ratio of air and flue gas entering the blower 503.

[0040] It should be noted that the aforementioned combustion furnace 300 can be a rotary kiln structure, a fluidized bed incinerator structure, or a mechanical grate furnace structure, etc., as long as the structure can meet the usage requirements, it falls within the protection scope of this invention. Optionally, the combustion furnace 300 provided in this embodiment of the invention is a rotary kiln structure inclined to the horizontal plane, and the end of the combustion furnace 300 near the preheating furnace 200 is higher than the end of the combustion furnace 300 away from the preheating furnace 200, so that the fuel can slide from the end near the preheating furnace 200 to the end away from the preheating furnace 200 under its own weight, avoiding the need to set up an additional material propulsion mechanism in the combustion furnace 300, reducing the number of parts and lowering costs.

[0041] It should be understood that the present invention does not specifically limit the degree of inclination of the combustion furnace 300. The degree of inclination of the fuel furnace 300 can be adjusted according to the type, particle size and processing capacity of the fuel. Any degree of inclination that can meet the usage requirements is within the protection scope of the present invention. Optionally, the angle between the combustion furnace 300 and the horizontal plane provided in the embodiment of the present invention is 5°.

[0042] The preheating furnace 200 provided by the present invention is a horizontally arranged rotary kiln structure, and the inner wall of the preheating furnace 200 is provided with inner spiral blades and baffles connecting the inner spiral blades, so as to push the fuel through the inner spiral blades and scatter and disturb the fuel through the baffles, thereby achieving efficient heat exchange between the fuel and the high-temperature flue gas and improving the preheating efficiency of the fuel.

[0043] Furthermore, this invention does not specifically limit the number of air distribution ducts 502; any number that meets the usage requirements falls within the scope of protection of this invention. Optionally, such as Figure 1 and Figure 2 As shown, the embodiment of the present invention provides three air distribution ducts 502, namely a first air distribution duct 5021, a second air distribution duct 5022, and a third air distribution duct 5023. The first air distribution duct 5021 is equipped with a primary air duct valve, the second air distribution duct 5022 is equipped with a secondary air duct valve, and the third air distribution duct is equipped with a tertiary air duct valve. The primary air duct valve controls the air intake in the first air distribution duct, the secondary air duct valve controls the air intake in the second air distribution duct, and the tertiary air duct valve controls the air intake in the third air distribution duct, thereby controlling the air intake through the first air distribution duct 5021, the second air distribution duct 5022, and the third air distribution duct 5023. 021. The second air distribution duct 5022 and the third air distribution duct 5023 rationally distribute the high-temperature air from the air preheater 501 and send it into the combustion furnace 300, enabling stable and complete combustion of low-volatile, low-calorific-value fuels within the combustion furnace 300. This achieves large-scale, continuous, and stable processing of low-volatile, low-calorific-value fuels, solving the technical challenge of large-scale, stable processing of such fuels in existing technologies. Simultaneously, the rational distribution of airflow through multiple stages ensures a reducing atmosphere in the main combustion zone at the front of the combustion furnace, achieving low NO₂ levels without the need for flue gas treatment equipment. xCombustion saves on equipment investment costs.

[0044] The terms "first" and "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units may include steps or units not listed, but rather steps or units not listed.

[0045] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fuel preheating combustion system, characterized in that, include: A conveying device used to transport fuel; A preheating furnace connected to the conveying device is used to preheat the fuel; A combustion furnace connected to the preheating furnace is used to receive and burn the fuel output from the preheating furnace; A boiler connected to the flue gas outlet of the combustion furnace, the boiler being provided with a cavity for holding a liquid medium; A multi-stage air distribution device, comprising an air preheater connected to the flue gas outlet of the boiler and capable of communicating with air, and multiple air distribution pipelines connecting the air preheater to the combustion furnace, the multiple air distribution pipelines being evenly distributed along the length of the combustion furnace, and each air distribution pipeline being equipped with an air path control valve. The flue gas outlet of the air preheater is connected to the preheating furnace; It also includes a central controller, an outlet fuel temperature controller installed in the preheating furnace, and a friction temperature controller installed in the combustion furnace. The outlet fuel temperature controller, the friction temperature controller, and the multi-stage air distribution device are all electrically connected to the central controller. It also includes an online flue gas monitoring device installed at the end of the combustion furnace. Both the online flue gas monitoring device and the material conveying device are electrically connected to the central controller. The online flue gas monitoring device monitors the O2, CO, and NO content in the ultra-high temperature flue gas near the combustion furnace outlet. x The components are monitored in real time, and the monitoring results are fed back to the central controller. The central controller then adjusts the fuel input of the conveying device and the air supply of the multi-stage air distribution device in a timely manner based on the monitoring results, the fuel temperature information at the preheating furnace outlet, and the temperature information along the combustion furnace.

2. The fuel preheating combustion system according to claim 1, characterized in that, It also includes an outlet flue gas pipeline connected to the preheating furnace, an induced draft fan installed in the outlet flue gas pipeline, and a chimney connected to the outlet flue gas pipeline.

3. The fuel preheating combustion system according to claim 2, characterized in that, It also includes a flue gas recirculation pipeline, which connects the outlet flue gas pipeline and the air preheater, and the flue gas recirculation pipeline is equipped with an opening control valve.

4. The fuel preheating combustion system according to claim 1, characterized in that, The multi-stage air distribution device also includes a blower for supplying air to the air preheater.

5. The fuel preheating combustion system according to claim 1, characterized in that, The combustion furnace is a rotary kiln structure inclined to the horizontal plane, with the end of the combustion furnace closer to the preheating furnace being higher than the end of the combustion furnace farther from the preheating furnace.

6. The fuel preheating combustion system according to claim 1, characterized in that, The preheating furnace is a horizontally arranged rotary kiln structure, and the inner wall of the preheating furnace is provided with inner spiral blades and partitions connecting the inner spiral blades.

7. The fuel preheating combustion system according to claim 1, characterized in that, The number of air distribution ducts is three, namely the first air distribution duct, the second air distribution duct and the third air distribution duct. The first air distribution duct is equipped with a primary air duct valve, the second air distribution duct is equipped with a secondary air duct valve, and the third air distribution duct is equipped with a tertiary air duct valve.

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