Air combustion system of waste incineration power plant

Abstract

The invention discloses an air combustion system of a waste incineration power plant. The air combustion system comprises a primary air system and a secondary air system. The primary air system comprises a primary air fan and a primary air suction inlet connected with the primary air fan, and the primary air suction inlet is formed in the upper portion of the dump pit and used for extracting air above the dump pit to maintain negative pressure of the dump pit. The secondary air system comprises a secondary fan and a plurality of secondary air suction ports connected with the secondary fan, namely a first air suction port arranged above the garbage pit, a second air suction port arranged above the slag pit, a third air suction port used for extracting cooling air of the pusher, and a fourth air suction port arranged above the leachate hopper near the pusher; and the negative pressure device is used for extracting air from the multiple odor source points at the same time to maintain the negative pressure environment, and the extracted air serves as secondary air to be fed into the incinerator. By the adoption of the system, negative pressure control over multiple odor source points can be achieved, so that part of independent odor control facilities are omitted, and the purposes of system collaboration, energy conservation and consumption reduction are achieved.

Description

Technical Field

[0001] This invention relates to the field of waste incineration technology, specifically to an air combustion system for a waste-to-energy plant. Background Technology

[0002] Waste-to-energy incineration is a crucial technology for reducing, rendering harmless, and recycling municipal solid waste. In the incineration process, the combustion air system is a core component, typically consisting of primary and secondary air. Primary air is mainly introduced from the bottom of the grate to dry the waste, provide oxygen to the main combustion zone, and cool the grate. Secondary air is injected from the top of the furnace, enhancing turbulence to promote flue gas mixing and ensure complete combustion, which is essential for reducing the formation of pollutants such as dioxins and CO.

[0003] Currently, approximately 60% of waste incineration projects use ambient air from the boiler room as a supplementary air source for secondary air or even primary air. This method of air source selection is relatively singular and has the following significant drawbacks: (1) Single air source and poor system coordination: Existing technology does not make full use of other points in the plant area that need to maintain negative pressure to prevent odor from overflowing (such as slag pit, pusher area, leachate hopper, etc.) as air intake points.

[0004] (2) Energy consumption and equipment redundancy: In order to control the spread of odor, these odor sources in the plant area need to create and maintain a negative pressure environment through independent HVAC systems. This increases the investment and operating energy consumption of additional equipment such as fans and ducts, resulting in the separation between systems and energy waste.

[0005] Therefore, there is an urgent need for an air combustion system that can integrate air sources, achieve system synergy, and effectively solve the problem of odor control. Summary of the Invention

[0006] This invention aims to overcome the aforementioned deficiencies of the prior art and provide an air combustion system for a waste incineration power plant. The main technical problem this invention addresses is: how to optimize the selection of air sources for the primary and secondary air systems to achieve negative pressure control of multiple odor sources while meeting combustion requirements, thereby eliminating the need for some independent odor control facilities and achieving system synergy, energy saving, and consumption reduction.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: An air combustion system for a waste incineration power plant includes a primary air system and a secondary air system.

[0008] The primary air system includes a primary air fan, a primary air inlet, a primary air steam preheater, and corresponding air ducts and regulating components. Its core improvement lies in the fact that the primary air inlet is located at the top of the garbage pit to draw air from above. This provides a source of primary air and maintains a stable negative pressure in the garbage pit, effectively preventing the escape and accumulation of odorous and combustible gases.

[0009] The secondary air system includes a secondary air fan, multiple secondary air inlets, secondary air nozzles, and corresponding air ducts and regulating components. Its core improvement lies in the fact that the multiple secondary air inlets are respectively located at multiple odor source points where negative pressure needs to be maintained. Specifically, these inlets include: a first inlet located above the waste pit, a second inlet located above the slag pit, a third inlet for extracting cooling air from the pusher, and a fourth inlet located above the leachate hopper near the pusher. By simultaneously or selectively extracting air from these four locations, the secondary air fan actively creates a negative pressure environment at these odor source points while meeting the secondary air volume requirements, thus replacing or reducing the burden on the original HVAC system.

[0010] Furthermore, the third air intake is connected to the cooling path of a pusher cooling fan. The inlet of the pusher cooling fan draws air locally in the incineration chamber, and its outlet is connected to the pusher for cooling the pusher. The hot air after heat exchange by the pusher is drawn in by the third air intake, so that the pusher cooling air is finally sent into the incinerator as a secondary air source, realizing the cascade utilization of energy.

[0011] Preferably, each secondary air intake branch of the secondary air system is equipped with a damper, which can flexibly switch or adjust the air volume ratio of each intake according to the odor concentration and combustion requirements of each odor source.

[0012] Preferably, the secondary air system delivers secondary air into the incinerator through multiple secondary air nozzles, which are arranged at the throat of a passage in the furnace. Each air supply branch pipe at the outlet of the secondary air fan is equipped with a flow meter and a regulating damper to achieve independent control of the air volume of each secondary air nozzle.

[0013] Preferably, the primary air system supplies air to multiple ash hoppers below the incinerator grate through multiple air distribution ducts. Each air distribution duct is equipped with an independent flow meter and regulating damper to achieve independent and precise control of the primary air volume in each zone. More specifically, the incinerator grate has four sections, corresponding to the drying zone, ignition zone, combustion zone, and burnout zone, with the grate height decreasing sequentially in a stepped manner. At the bottom of each grate are four ash hoppers arranged sequentially along the waste conveying direction. This structure, combined with independent zoned air supply control, can precisely match the air requirements of each combustion stage.

[0014] Preferably, the primary air steam preheater adopts a two-stage heating method. The first stage uses primary steam extraction to heat the air to about 160°C, and the second stage uses steam extraction from the steam drum to heat the air to about 220°C. Its condensate is sent to the deaerator to recover the working fluid and heat.

[0015] Compared with the prior art, the air combustion system provided by the present invention has the following beneficial effects: 1. Highly efficient odor control and system synergy: By directly placing primary and secondary air sources at key odor emission points such as waste pits, slag pits, and leachate hoppers, the "air intake" process required for combustion and the "maintaining negative pressure" process required for environmental protection are combined into one. This eliminates or significantly reduces the need for separate negative pressure exhaust systems at these locations, achieving deep synergy between the combustion and environmental protection systems and simplifying the overall plant system configuration.

[0016] 2. Energy saving and consumption reduction, improving energy utilization efficiency: The pusher cooling air is fully utilized as a secondary air source, introducing the hot air used for equipment cooling into the furnace to participate in combustion, recovering this heat and avoiding energy waste. At the same time, the operation of independent heating and ventilation fans is reduced, directly lowering the plant's power consumption.

[0017] 3. Optimized combustion and reduced pollutant emissions: The multi-source air design allows for secondary air temperature and composition that are more conducive to combustion organization. Combined with zoned air supply control and a stepped grate structure, the optimal air volume and temperature can be provided for each stage of waste drying, ignition, combustion, and burnout, greatly improving combustion conditions, promoting fuel burnout, and thus effectively reducing the generation of pollutants such as CO, unburned carbon, and dioxins.

[0018] 4. Enhanced operational flexibility and reliability: The secondary air intakes are equipped with independent dampers, allowing for flexible adjustment of the air supply ratio based on seasonal changes, waste composition variations, and other factors, thus enhancing the system's adaptability to complex operating conditions. High system integration and reduced equipment redundancy also improve overall operational reliability. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the air combustion system provided in an embodiment of the present invention.

[0020] Numbering on the map: 1-Primary air fan, 11-Primary air inlet, 2-Secondary air fan, 21-Secondary air inlet, 21a-First air inlet, 21b-Second air inlet, 21c-Third air inlet, 21d-Fourth air inlet, 3-Pusher cooling fan, 10-Garbage pit, 20-Slag pit, 30-Pusher, 40-Leachate hopper, 50-Incinerator grate, 51-Ash hopper, 4-Damper, 6-Flow meter, 5-Primary air steam preheater, 7-Regulating damper, 8-Secondary air nozzle, 9-Metal filter screen, 12-Silencer, 13-Isolation door. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and for simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] like Figure 1 As shown in the figure, the air combustion system of the waste incineration power plant of the present invention mainly consists of a primary air system and a secondary air system.

[0024] Primary air system: The primary air system is responsible for supplying air to the air chamber below the grate. Its main functions include: providing oxygen for waste combustion, maintaining the excess air coefficient between 1.05 and 1.2 to ensure complete combustion, drying and preheating the waste, and cooling the grate structure to extend the equipment life.

[0025] The primary air system includes a primary air fan 1, a primary air inlet 11, a primary air steam preheater 5, and corresponding air ducts, flow meters 6, and regulating dampers 7. The primary air fan 1 is generally a centrifugal fan, and the air volume is controlled by frequency conversion and inlet damper.

[0026] The primary air intake 11 is located at the top of the garbage pit 10. This provides a source of primary air and creates and maintains a stable negative pressure inside the garbage pit 10, effectively preventing the escape and accumulation of odorous and combustible gases. To prevent the inhalation of foreign objects, a metal filter 9 is installed at the primary air intake 11, and a silencer 12 is installed on the air duct to reduce noise.

[0027] A primary air steam preheater 5 is installed on the outlet duct of the primary air fan 1. Preferably, the preheater 5 employs a two-stage heating method: the first stage uses primary steam extraction to heat the air to approximately 160°C, and the second stage uses steam extraction from the steam drum to heat the air to the required 220-230°C, to accommodate waste with different calorific values. The condensate from the preheater 5 is sent to a deaerator to recover the working fluid and heat.

[0028] The heated primary air is delivered through the main air duct. Regarding the grate structure, in this embodiment, the entire grate is divided into four zones. Each zone has four ash hoppers / air chambers 51 arranged along the waste conveying direction at its bottom, totaling 16 ash hoppers. The main air duct is correspondingly divided into 16 branch pipes, each equipped with an independent flow meter 6 and a regulating damper 7. This allows for independent and precise control of the airflow to each ash hopper, meeting the different airflow requirements of each combustion zone and preventing the material layer from being blown through.

[0029] Secondary air system: The main function of the secondary air system is to enhance the turbulence of flue gas in the furnace, promote the full mixing of unburned gases with oxygen, and prolong the residence time of flue gas, thereby optimizing combustion efficiency and reducing pollutant emissions.

[0030] The secondary air system includes a secondary air fan 2, multiple secondary air inlets 21, secondary air nozzles 8, and corresponding air ducts, dampers (4 and 7), and a flow meter 6. The secondary air fan 2 is preferably a centrifugal fan, and is adjusted by frequency conversion and inlet baffle.

[0031] The secondary air system is equipped with multiple secondary air inlets 21, which draw air from the odor source points where negative pressure needs to be maintained. Specifically, it includes: The first air intake 21a is located above the garbage pit 10; The second air intake 21b is located above the slag pit 20; The third air intake 21c is connected to the cooling air path of the pusher 30; The fourth air intake 21d is located above the percolate hopper 40 near the pusher 30.

[0032] Each air intake (21a, 21b, 21c, 21d) branch is equipped with a manual or electric damper 4 for opening, closing, and adjustment, allowing for flexible switching or adjustment of the airflow ratio according to the actual conditions of each odor point. Similarly, a metal filter 9 can be installed at each air intake (21a, 21b, 21c, 21d), and a silencer 12 can be installed on the air duct.

[0033] The outlet duct of the secondary air fan 2 leads to the furnace, and multiple secondary air nozzles 8 are arranged in two rows at the throat of the furnace passage. Adjustable dampers 7 and flow meters 6 are also installed on the branch pipes leading to different nozzles or nozzle groups to achieve independent control of the airflow of each nozzle.

[0034] Specifically, the integration of the pusher cooling air is as follows: the system is equipped with a separate pusher cooling fan 3, whose inlet is located in the combustion chamber for on-site air intake, and whose outlet is connected to the pusher 30 for cooling. The hot air after heat exchange by the pusher is guided to the third air intake 21c for extraction, so that the pusher cooling air is ultimately sent into the furnace as a secondary air source, realizing the cascade utilization of energy.

[0035] The working process of the air combustion system in the waste-to-energy plant according to an embodiment of the present invention is as follows: Primary air flow: After system startup, the primary air fan 1 draws air from the top of the waste pit 10 to maintain negative pressure within the pit. The drawn-in ambient temperature air is pressurized by the fan and heated to approximately 220°C by the primary air steam preheater 5. The hot air is then delivered to the 16 ash hoppers 51 at the bottom of the grate 50 through 16 independent branch pipes. The distributed control system independently adjusts the opening of the regulating dampers 7 of each branch pipe based on the temperature and oxygen sensor signals measured by thermocouples in each grate area, providing precisely matched air volume and temperature for different stages such as drying, combustion, and burnout.

[0036] Secondary air process: Secondary air fan 2 starts, simultaneously drawing air from four secondary air inlets 21. This suction creates negative pressure above the waste pit 10 (secondary supplementary suction), slag pit 20, leachate hopper 40, and the pusher cooling air outlet, preventing odor leakage from these points. The multi-source air is mixed and pressurized by secondary air fan 2, then injected into the upper part of the furnace as a high-speed jet through nozzles 8. The jet strongly disturbs the flue gas, prolonging its residence time and ensuring complete combustion of combustible components. Operators can optimize combustion by adjusting the secondary air main flow rate and the proportion of each air inlet damper 4 according to the CO and O2 concentrations at the furnace outlet. To prevent nozzle thermal damage, a minimum secondary air flow rate must always be maintained.

[0037] The pusher cooling air integration process: The pusher cooling fan 3 operates independently. After completing the cooling task of the pusher 30, its cooling air temperature rises, carrying heat. This hot air is no longer directly discharged into the environment, but is drawn away by the secondary air system as a "free" air source and finally sent into the furnace, thus recovering heat and contributing air volume.

[0038] Therefore, this system introduces the hot air from the outlet of the pusher cooling fan 3 into the secondary air source, realizing the synergy of equipment cooling and combustion assistance; it deeply integrates the air intake functions of primary and secondary air with the odor control requirements of the plant area, and replaces some auxiliary environmental protection facilities with the main combustion process, achieving the goal of system interconnection and interoperability, energy saving and consumption reduction.

[0039] Based on the above basic embodiments, the present invention may also have other configurations to achieve higher system reliability, more flexible adjustment capabilities, or adaptability to specific factory layouts.

[0040] In a preferred embodiment of the present invention, the primary air system can be arranged into multiple independent subsystems. For example, two independent primary air systems can be set up, namely a first primary air system and a second primary air system.

[0041] Air source configuration: The primary air intake of the first primary air system can be located above area A of the garbage pit 10, while the primary air intake of the second primary air system is located above area B of the garbage pit 10. This configuration can more evenly and effectively create negative pressure control over a large area inside the garbage pit, avoiding problems such as airflow short-circuiting or uneven negative pressure caused by a single air intake.

[0042] Air supply configuration: On the air supply side, the outlet headers of the two primary air fans 1 can be interconnected via connecting air ducts and equipped with isolation doors 13 for mutual backup, or they can operate independently. Considering the distribution of the 16 ash hoppers 51 at the bottom of the grate (4 zones, 4 ash hoppers per zone), air supply responsibilities can be cross-assigned to maximize redundancy and reliability. For example, the first primary air system can drive two ash hoppers in each zone of the grate, totaling 8 ash hoppers; the second primary air system can drive the other two ash hoppers in each zone of the grate, totaling 8 ash hoppers. Each branch within the primary air system still maintains an independent flow meter 6 and regulating damper 7.

[0043] During normal operation, the two primary air systems independently adjust the air volume and temperature according to the combustion needs of their respective ash hopper areas. When the fan or critical equipment of one system (such as the primary primary air system) needs maintenance, the isolation door 13 of the connecting air duct can be closed to isolate it. The other normally operating system (the secondary primary air system) can then temporarily take over the air supply for all 16 ash hoppers by increasing the fan output. Because the air supply capacity of each area is partially preserved, rather than completely lost, this cross-allocation method can significantly improve operational stability and combustion continuity under fault conditions.

[0044] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An air combustion system for a waste-to-energy incineration plant, characterized in that, Includes primary air system and secondary air system; The primary air system includes a primary air fan and a primary air inlet connected thereto. The primary air inlet is located at the top of the garbage pit and is used to extract air from above the garbage pit to maintain negative pressure in the garbage pit. The secondary air system includes a secondary air fan and multiple secondary air inlets connected to it. The multiple secondary air inlets are respectively set at multiple odor source points that need to maintain negative pressure, including a first air inlet set above the waste pit, a second air inlet set above the slag pit, a third air inlet set for extracting cooling air from the pusher, and a fourth air inlet set above the leachate hopper near the pusher. It is used to simultaneously extract air from the multiple odor source points to maintain their negative pressure environment, and send the extracted air as secondary air into the incinerator.

2. The air combustion system according to claim 1, characterized in that, The third air intake is connected to the cooling path of a pusher cooling fan; The inlet of the pusher cooling fan is drawn in on-site in the incineration chamber, and its outlet is connected to the pusher for cooling the pusher; the air coming out of the pusher is drawn in by the third air inlet, so that the pusher cooling air is finally sent into the incinerator as a secondary air source.

3. The air combustion system according to claim 1, characterized in that, Each secondary air intake branch of the secondary air system is equipped with a damper, which is used to switch or adjust the air volume of each intake according to actual operating requirements.

4. The air combustion system according to claim 1, characterized in that, The primary air system also includes a primary air steam preheater installed on the outlet duct of the primary air fan, used to heat the primary air to the required temperature.

5. The air combustion system according to claim 4, characterized in that, The primary air steam preheater adopts at least two-stage heating. The first stage uses single-stage extraction steam heating, and the second stage uses steam drum extraction steam heating. Its condensate is sent to the deaerator to recover the working fluid and heat.

6. The air combustion system according to claim 1, characterized in that, The primary air system supplies air to multiple ash hoppers below the incinerator grate through multiple air distribution ducts. Each air distribution duct is equipped with an independent flow meter and regulating damper to achieve independent and precise control of the primary air volume in each area.

7. The air combustion system according to claim 6, characterized in that, The incinerator has four grates, corresponding to the drying zone, ignition zone, combustion zone and burnout zone respectively. The height of the incinerator grates in each zone decreases in a stepped manner. At the bottom of each incinerator grates are four ash hoppers arranged sequentially along the waste conveying direction.

8. The air combustion system according to claim 1, characterized in that, The secondary air system delivers secondary air into the incinerator through multiple secondary air nozzles, which are located at the throat of a passage in the furnace. Each branch pipe at the outlet of the secondary air fan is equipped with a flow meter and a regulating damper to achieve independent control of the air volume of each secondary air nozzle.

9. The air combustion system according to claim 1, characterized in that, Metal filters are installed at the primary air intake and / or secondary air intake to prevent the intake of foreign objects; and silencers are installed on the intake duct to reduce noise.

10. The air combustion system according to any one of claims 1-9, characterized in that, Both the primary and secondary air fans are centrifugal fans and are equipped with frequency converters and / or inlet damper adjustment devices for air volume control.

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