Fly ash high-temperature internal circulation stable combustion system and method integrated with climbing optimization

Abstract

The invention discloses a fly ash high-temperature internal circulation stable combustion system and method integrated with climbing optimization, and the system comprises a fly ash extraction module which is arranged at a flue vertical section between a boiler economizer and an air preheater and is used for extracting high-temperature fly ash; the fly ash conveying module is connected with the fly ash extraction module and is used for carrying out gas-solid separation and caching on the extracted fly ash and conveying the fly ash in a dense-phase flow state; the fly ash injection modules are circumferentially arranged on the periphery of a boiler wall of a boiler main burner area; the intelligent control system comprises a basic control layer and a combustion enhancement feedforward control module, and the basic control layer is used for adjusting fly ash reinjection flow to be matched with the current load according to a boiler load instruction and a real-time combustion signal; the combustion strengthening feedforward control module controls the fly ash reinjection amount to be increased to peak flow, and preheating saturation treatment is conducted on a combustion area; and the climbing rate of the unit is improved through the dual effects of preheating saturation and thermal pulse.

Description

Technical Field

[0001] This invention relates to the field of clean combustion technology for coal-fired boilers, specifically to an integrated slope-optimized high-temperature internal circulation stable combustion system and method for fly ash. Background Technology

[0002] When a coal-fired boiler operates at low load, the reduced furnace temperature makes it difficult for pulverized coal to ignite. Existing technologies commonly employ flue gas recirculation or hot air recirculation, but these methods suffer from high fan power consumption and system complexity. Fly ash, as a solid residue from pulverized coal combustion, typically has a temperature above 800°C and contains significant sensible heat; however, in traditional technologies, this heat is wasted as it is discharged into the tail flue with the flue gas. How to safely and efficiently extract and return high-temperature fly ash to the furnace combustion zone, utilizing its physical heat for preheating and stable combustion, is a significant technical challenge. Furthermore, during rapid load increases, relying solely on the physical heat of fly ash for preheating still suffers from thermal inertia, requiring a faster start-up mechanism to overcome this initial inertia bottleneck. Summary of the Invention

[0003] The purpose of this invention is to propose an integrated slope-optimized high-temperature internal circulation stable combustion system and method for fly ash to solve the problems mentioned in the background art.

[0004] To achieve the above-mentioned objectives, the first technical solution adopted by the present invention is: a high-temperature internal circulation stable combustion system for fly ash with integrated slope optimization, comprising: a fly ash extraction module, a fly ash conveying module, a fly ash injection module, and an intelligent control system; The fly ash extraction module is installed in the vertical section of the flue between the boiler economizer and the air preheater, and is used to extract high-temperature fly ash. The fly ash conveying module is connected to the fly ash extraction module and is used to perform gas-solid separation, buffering, and conveying of the extracted fly ash in a dense phase flow state. The fly ash injection module is circumferentially arranged around the furnace wall in the main burner area of ​​the boiler, and is used to evenly inject fly ash into the furnace to form a fly ash curtain covering the burner area. The intelligent control system is communicatively connected to the fly ash extraction module, the conveying and storage module, and the injection module, and includes a basic control layer and a combustion enhancement feedforward control module. The basic control layer is used to adjust the fly ash reinjection flow rate to match the current load according to the boiler load command and real-time combustion signal; The combustion enhancement feedforward control module is used to communicate with the automatic generation control (AGC) system or load forecasting system of the power grid. 60-90 seconds before the boiler load increase coal feeding command is executed, it controls the fly ash reinjection to increase to the peak flow rate and preheats and saturates the combustion zone.

[0005] Furthermore, the fly ash conveying module includes a cyclone separator, a fly ash buffer bin, a rotary feeder valve, and a dense phase conveying pump; the cyclone separator is used to separate ≥95% of the fly ash and let it fall into the fly ash buffer bin, which is equipped with a fluidizing device to prevent fly ash caking and maintain stable material level; the rotary feeder valve feeds the fly ash quantitatively into the dense phase conveying pump, which uses compressed air as power to convey the fly ash to the furnace at a solid-gas ratio of 20-40 kg ash / kg air.

[0006] Furthermore, the fly ash extraction module includes a negative pressure extractor connected to a cyclone separator. The bottom outlet of the cyclone separator is connected to a fly ash buffer chamber. The negative pressure extractor generates negative pressure through a high-pressure fan to extract the fly ash and a small amount of flue gas mixed in the flue and then connected to the cyclone separator to achieve preliminary gas-solid separation.

[0007] Furthermore, the negative pressure extractor includes a venturi tube, a gas supply regulating valve, and a wear-resistant ceramic liner. The end of the negative pressure extractor is provided with an extraction port, and the extraction port is equipped with a grid filter.

[0008] Furthermore, the fly ash injection module includes multiple adjustable wear-resistant nozzles arranged circumferentially in the furnace burner area. The adjustable wear-resistant nozzles are equipped with swirl vanes inside, and the swirl vanes are arranged below or to the side of the secondary air nozzle of the main burner.

[0009] Furthermore, the adjustable wear-resistant nozzle is connected to an injection pipeline, which is equipped with a pneumatic quick-closing valve and a flow regulating valve for precise control of the fly ash injection timing and flow rate.

[0010] Furthermore, it also includes a fuel auxiliary module, which includes an atomized fuel spray gun, a high-pressure oil / gas supply system, and a fast-acting valve; the fuel auxiliary module is configured to inject a small amount of auxiliary fuel into the furnace to generate a heat pulse during the initial stage of the boiler's rapid load increase process.

[0011] Furthermore, the intelligent control system is also equipped with a fault alarm module. When the fly ash extraction volume, conveying pressure, or injection flow rate deviates from the set threshold by ±10%, an alarm signal is immediately issued and the system switches to manual control mode.

[0012] To achieve the aforementioned objectives, the second technical solution adopted by this invention is: a method for stable combustion of fly ash in high-temperature internal circulation with integrated slope-climbing optimization, comprising the following steps: S1, Low-load stable combustion control: When the boiler load is in the range of 15%-20% of the rated load, the fly ash reinjection amount is adjusted through the basic control layer of the intelligent control system. S2, Combustion Enhancement Feedforward Preheating: When the trend of the grid AGC load increase command is detected and the slope is greater than the set value, the combustion enhancement feedforward control module is started 60-90 seconds before the load increase coal feeding command is executed, and the fly ash reinjection amount is increased to the peak flow rate to preheat the combustion zone. S3, Rapid Climbing Coordinated Enhancement: When the load increase coal feeding command is executed, the target climbing rate is analyzed. If the target climbing rate is greater than or equal to the set threshold, a small amount of auxiliary fuel is injected to generate a heat pulse to accelerate the load response. S4, Steady-state recovery: When the load ramp-up rate reaches the target value and the furnace combustion stabilizes, gradually reduce the fly ash reinjection amount to a steady-state value that matches the current load, and stop auxiliary fuel injection.

[0013] Furthermore, in step S4, after the load climbs up and stabilizes, the rate of decrease in fly ash reinjection is 0.5-1 t / h.

[0014] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: 1. Strong low-load stable combustion capability, enabling the boiler to operate safely and stably for a long time under 15%-20% BMCR load, and widening the lower limit of peak shaving.

[0015] 2. Significantly improves ramp performance: The unit's ramp rate is improved through the dual effects of preheating saturation and thermal pulse.

[0016] 3. Synergistic environmental protection and energy saving: High-temperature fly ash reinjection creates a local reducing atmosphere, inhibits NOx generation, reduces SCR inlet concentration, and unburned carbon in fly ash undergoes secondary combustion in the furnace, improving boiler efficiency.

[0017] 4. Excellent investment and operating economy: The main equipment of the system is conventional material conveying equipment with mature technology. The main operating cost is the power consumption of the fan and air compressor. The energy consumption is low, and the fuel auxiliary input is minimal, so the cost is controllable. Attached Figure Description

[0018] Figure 1 This shows a block diagram of the integrated ramp-up optimized high-temperature internal circulation stable combustion system for fly ash provided in an embodiment of the present invention; Figure 2 The diagram shows a logic block diagram of the boiler stable combustion ramping method based on multi-stage vortex and intelligent feedforward provided in the embodiments of the present invention. Figure 3 The flowchart shows the method based on multi-stage vortex and intelligent feedforward provided by the embodiments of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. 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 system that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or systems.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] like Figure 1 As shown, this embodiment of the invention provides a fly ash high-temperature internal circulation stable combustion system with integrated slope optimization, including: a fly ash extraction module, a fly ash conveying module, a fly ash injection module, and an intelligent control system; The fly ash extraction module is installed in the vertical section of the flue between the boiler economizer and the air preheater to extract high-temperature fly ash. Specifically, the fly ash extraction module sets the extraction point to be located in the vertical section of the flue between the boiler economizer and the air preheater. Here, the fly ash temperature is high (usually 450-600°C) and it is not cooled by the air preheater, so the carbon content is relatively low.

[0023] The fly ash conveying module is connected to the fly ash extraction module and is used to perform gas-solid separation, buffering, and conveying of the extracted fly ash in a dense phase flow state. It should be noted that the fly ash conveying module includes: Primary separation and buffering: The extracted gas-solid two-phase flow first enters a high-efficiency cyclone separator, which separates most of the fly ash (>95%), which falls into the buffer bin below. The buffer bin is equipped with a fluidization device (fluidizing plate or pneumatic slide plate) to prevent fly ash from caking and to maintain a stable material level within the bin.

[0024] Pressurized conveying: The rotary feeder valve (star-shaped unloader) under the buffer silo feeds the fly ash into a positive pressure dense phase conveying pump (such as a silo pump). The pump uses compressed air as power to convey the fly ash in a dense phase flow state with a high solid-to-gas ratio (20-40 kg ash / kg air) through wear-resistant ceramic composite pipes to the vicinity of the furnace.

[0025] The fly ash injection module is arranged circumferentially around the furnace wall in the main burner area of ​​the boiler to evenly inject fly ash into the furnace and form a fly ash curtain covering the burner area. The intelligent control system is communicatively connected to the fly ash extraction module, the conveying and storage module, and the injection module, and includes a basic control layer and a combustion enhancement feedforward control module. The basic control layer is used to adjust the fly ash reinjection flow rate to match the current load based on boiler load commands and real-time combustion signals; The combustion enhancement feedforward control module is used to communicate with the grid automatic generation control (AGC) system or load forecasting system. 60-90 seconds before the boiler load increase coal feeding command is executed, it controls the fly ash reinjection to increase to the peak flow rate and preheats and saturates the combustion zone.

[0026] Specifically, the basic control layer uses PID control to adjust the feeding frequency and gas delivery volume of the fly ash reinjection system based on boiler load commands and real-time combustion signals (such as flame monitoring and oxygen levels) to maintain the correlation between fly ash reinjection flow rate and boiler load. At low loads, the fly ash reinjection volume is increased to enhance stable combustion.

[0027] The combustion-enhanced feedforward control layer is deeply integrated with the grid dispatch command interface and the power plant load prediction system (such as based on electricity price forecasts). Its core idea is time substitution: 60-90 seconds before the formal receipt and execution of the AGC load increase command at time T0 (defined as T-60 to T-90), the control system initiates the feedforward action.

[0028] Feedforward action: Instructs the fly ash conveying system to reinject high-temperature fly ash into the furnace at maximum capacity (i.e., "peak flow rate"). This stage does not immediately increase the fuel quantity, but rather utilizes the enormous heat capacity and radiative power of the fly ash particles to preheat and saturate the furnace space in the burner area, the surface of the combustion zone, and even the primary air-coal flow.

[0029] Effect: When the coal mill starts adding coal at time T0, the new coal powder enters a "quasi-ignition" environment that has been fully preheated. Its physical ignition delay time (from heat absorption to ignition) is greatly compressed, even approaching zero, which buys critical time for subsequent rapid combustion and heat release.

[0030] It should be noted that the peak flow rate of the combustion enhancement feedforward control module corresponds to 2% of the ash content in the boiler MCR condition. The preheating saturation treatment target is to increase the average temperature of the burner area from about 1000℃ under low load to more than 1200℃, which is far beyond the ignition point of lean coal / anthracite.

[0031] According to an embodiment of the present invention, the fly ash conveying module includes a cyclone separator, a fly ash buffer bin, a rotary feeder valve, and a dense phase conveying pump; the cyclone separator is used to separate ≥95% of the fly ash and let it fall into the fly ash buffer bin, the fly ash buffer bin is equipped with a fluidization device to prevent fly ash caking and maintain stable material level; the rotary feeder valve feeds the fly ash quantitatively into the dense phase conveying pump, the dense phase conveying pump is powered by compressed air, and conveys the fly ash to the furnace at a solid-gas ratio of 20-40 kg ash / kg gas.

[0032] It should be noted that the fluidization device is a fluidizing plate or a pneumatic sliding plate, and the dense phase conveying pump is a silo pump with a conveying distance not exceeding 80 meters and a lifting height not exceeding 30 meters, adapting to the installation layout requirements of the unit boiler.

[0033] According to an embodiment of the present invention, the fly ash extraction module includes a negative pressure extractor connected to a cyclone separator. The bottom outlet of the cyclone separator is connected to a fly ash buffer chamber. The negative pressure extractor generates negative pressure through a high-pressure fan to extract fly ash and a small amount of flue gas mixed in the flue and then connected to the cyclone separator to achieve preliminary gas-solid separation.

[0034] According to an embodiment of the present invention, the negative pressure extractor includes a venturi tube, a gas supply regulating valve and a wear-resistant ceramic liner. The end of the negative pressure extractor is provided with an extraction port, and the extraction port is provided with a grid filter.

[0035] The negative pressure extractor is a negative pressure dilute phase pneumatic conveying extractor, and the high-pressure blower is a Roots blower.

[0036] According to an embodiment of the present invention, the fly ash injection module includes multiple adjustable wear-resistant nozzles arranged circumferentially in the furnace burner area. The adjustable wear-resistant nozzles are provided with swirl vanes inside. The swirl vanes are arranged below or to the side of the secondary air nozzle of the main burner to avoid interfering with the primary air-coal airflow.

[0037] Specifically, the fly ash precision injection module has multiple (usually 8-16) dedicated injection ports around the furnace wall at the same elevation in the main burner area. Each injection port is connected to a wear-resistant nozzle with adjustable angle and diffusion. The nozzle is equipped with a swirl vane to allow the fly ash flow to diffuse appropriately when injected into the furnace, forming a high-temperature fly ash curtain covering the burner area.

[0038] According to an embodiment of the present invention, the adjustable wear-resistant nozzle is connected to an injection pipeline, which is equipped with a pneumatic quick-closing valve and a flow regulating valve for precise control of the fly ash injection timing and flow rate.

[0039] According to an embodiment of the present invention, it further includes a fuel auxiliary module, which includes an atomizing fuel spray gun, a high-pressure oil / gas supply system, and a fast-acting valve; the fuel auxiliary module is configured to inject a small amount of auxiliary fuel into the furnace to generate a heat pulse during the initial stage of the boiler's rapid load increase process.

[0040] Specifically, two mechanical atomizing oil guns are provided as spray nozzles for the rapid response fuel auxiliary module. Each oil gun has a capacity of 300 kg / h and a supply pressure of 2.5 MPa, meeting the power requirements of micro-pulse injection. The mechanical atomizing oil guns use mechanical atomization or high-pressure air atomization, with an atomized particle size ≤50 μm, ensuring that the auxiliary fuel completes evaporation and combustion in milliseconds in the high-temperature fly ash environment.

[0041] The intelligent control system also includes an auxiliary control module, which is configured to: when the target climbing rate is higher than 3.0%Pe / min, trigger the fuel auxiliary module to execute a quantitative, limited-duration fuel injection pulse at the same time as or 1-2 seconds after the load increase coal feeding command is executed, with a total injection volume of 200-500kg and a duration of 60-90 seconds, and execute in parallel with the coal feeding command.

[0042] It should be noted that the auxiliary control module specifically includes: Mechanism: This strategy serves as a supplement and enhancement to feedforward control, specifically designed to overcome the thermal inertia bottleneck in the initial 1-2 minutes of ramp-up (critical period for power grid assessment).

[0043] Triggering condition: Automatically triggered when the system performs a rapid ramp and the target ramp rate is higher than the set threshold (e.g., >3.0% / min).

[0044] Action sequence: At time T0 (or slightly delayed by 1-2 seconds, after the pulverized coal begins to enter the furnace), the fuel auxiliary system is started.

[0045] Control mode: Open-loop pulse control is adopted. The system calculates an optimal total auxiliary fuel volume and injection duration based on the target climbing rate (e.g., total fuel volume 200-500 kg, continuous injection for 60-90 seconds). The high-speed solenoid valve opens, and fuel with high atomization quality is injected into the main combustion zone, which has been preheated by high-temperature fly ash.

[0046] Synergistic effect: In a high-temperature, oxygen-rich environment filled with hot fly ash particles, atomized fuel completes evaporation, mixing, and combustion within milliseconds, releasing a violent but controllable heat pulse. This heat pulse produces a triple effect: It directly contributes a portion of the steam power, enabling an instantaneous initial surge in load; It rapidly increases the local temperature, igniting and intensely stimulating the surrounding newly introduced coal dust; The mixing of high-temperature gas and fly ash particles further enhances the radiative heat transfer to the subsequent pulverized coal airflow.

[0047] Cost control: The auxiliary fuel is input in a trace amount and intermittently. Its cost has been accurately measured and can be fully covered by the additional income obtained from the rapid ramp-up auxiliary service with a surplus.

[0048] According to an embodiment of the present invention, the intelligent control system is also equipped with a fault alarm module. When the fly ash extraction amount, conveying pressure or injection flow rate deviates from the set threshold by ±10%, an alarm signal is immediately issued and the system switches to the manual control mode.

[0049] In a specific embodiment of the present invention, it is applied to the retrofit of a boiler supporting a 2×600MW unit, specifically as follows: 1. System design parameters: Design of fly ash treatment capacity per single furnace: The maximum reinjection amount is 20t / h (corresponding to about 2% of the ash amount under the boiler MCR condition); The normal low-load reinjection amount is 5 - 10 t / h. Fly ash temperature: At the extraction point, it is about 550°C. After the temperature drop during conveying, when it is injected into the furnace, it is not lower than 500°C.

[0050] Conveying distance: About 80 meters, lifting height 30 meters. Double bin pumps are used for alternating conveying to ensure continuity.

[0051] Injection points: On the four walls of the boiler, 1 meter below the burner layer, a total of 12 injection ports are arranged.

[0052] Fuel auxiliary system: Configure 2 mechanical atomizing oil guns, with a single capacity of 300kg / h and an oil supply pressure of 2.5MPa.

[0053] 2. Specific implementation of control logic includes: Add a "fly ash internal circulation optimization control" function block in the DCS.

[0054] Implementation of feedforward control: Write a dedicated script to monitor the change rate of the AGC command. When it is detected that the command has a continuous upward trend within the next 60 seconds and the slope is greater than the set value, immediately set the "feedforward activation" flag. This flag triggers 1) setting the fly ash reinjection flow control loop to the "maximum value" hold mode; 2) sending a "combustion zone preheated" status signal to the coordinated control system (CCS), and CCS can accordingly moderately optimize the coal feeding rate curve.

[0055] Implementation of fuel auxiliary control: When the feedforward is activated and the target ramp rate > 3.0% / min, the system automatically generates a fuel pulse command sequence (including: valve opening, flow ramp up, steady-state injection, flow ramp down, valve closing), and the total time and fuel quantity are calculated by the feedforward module. This sequence is executed in parallel with the coal feeding command of CCS.

[0056] 3. Operating effects include: Deep peak shaving: The unit can operate safely at 18% load, with stable fly ash reinjection, stable furnace negative pressure and flame TV signal, and no need for oil injection.

[0057] Rapid ramp test: The load is increased from 20% to 50%, and the ramp rate is required to be 3.5% / min.

[0058] T-75s: The system predicted the ramp-up demand and instantly increased the fly ash reinjection rate from 8t / h to 20t / h.

[0059] T0: The AGC command is issued, the coal feed rate begins to increase, and at the same time, the oil gun pulse is activated, spraying oil at a flow rate of 250 kg / h for 60 seconds.

[0060] T0-T+90s: The actual load curve closely follows the command curve. In the initial stage, there is a slight overshoot due to the contribution of the oil gun, but it quickly stabilizes. The average ramp rate reaches 3.6% / min. Throughout the process, the furnace heat load rises steadily and the main steam pressure is well controlled.

[0061] like Figures 2-3 As shown, to achieve the above-mentioned objective, the second technical solution adopted by this invention is: a method for stable combustion of fly ash in high-temperature internal circulation with integrated slope-climbing optimization, comprising the following steps: S1, Low-load stable combustion control: When the boiler load is in the range of 15%-20% of the rated load, the fly ash reinjection amount is adjusted through the basic control layer of the intelligent control system. Specifically, when the boiler load is in the range of 15%-20% of the rated load, the fly ash reinjection rate is adjusted to 5-10t / h through the basic control layer of the intelligent control system. The sensible heat of the fly ash is used to maintain the temperature of the furnace combustion zone at no less than 1000℃, thus achieving oil-free stable combustion.

[0062] S2, Combustion Enhancement Feedforward Preheating: When the trend of the grid AGC load increase command is detected and the slope is greater than the set value, the combustion enhancement feedforward control module is started 60-90 seconds before the load increase coal feeding command is executed, and the fly ash reinjection amount is increased to the peak flow rate to preheat the combustion zone. Specifically, when the trend of the power grid AGC load increase command is detected and the slope is greater than the set value, the combustion enhancement feedforward control module is started 60-90 seconds before the load increase coal feeding command is executed. The fly ash reinjection amount is increased to the peak flow rate (maximum 20t / h), and the furnace space, the surface of the combustion zone and the primary air-coal flow in the burner area are preheated and saturated, so that the average temperature of the combustion zone reaches above 1200℃.

[0063] S3, Rapid Climbing Coordinated Enhancement: When the load increase coal feeding command is executed, the target climbing rate is analyzed. If the target climbing rate is greater than or equal to the set threshold, a small amount of auxiliary fuel is injected to generate a heat pulse to accelerate the load response. Specifically, when the load increase coal feeding command is executed, if the target ramp rate is ≥3.0%Pe / min, the fast response fuel assistance module is activated to inject a small amount of auxiliary fuel to generate a heat pulse, which accelerates the initial load response. The heat pulse is used to directly contribute steam power, ignite pulverized coal and enhance radiative heat transfer.

[0064] S4, Steady-state recovery: When the load ramp-up rate reaches the target value and the furnace combustion stabilizes, gradually reduce the fly ash reinjection amount to a steady-state value that matches the current load, and stop auxiliary fuel injection.

[0065] Specifically, once the load ramp-up rate reaches the target value of ≥3.5%Pe / min and the furnace combustion stabilizes, the fly ash reinjection amount is gradually reduced to a steady-state value that matches the current load, and auxiliary fuel injection is stopped. The feedforward preheating action continues for at least 30 seconds after the load ramp-up coal feeding action begins.

[0066] According to an embodiment of the present invention, in step S4, after the load climbs up and stabilizes, the rate of decrease in fly ash reinjection is 0.5-1 t / h.

[0067] In summary, the present invention has the following advantages compared with the prior art: 1. Strong low-load stable combustion capability, enabling the boiler to operate safely and stably for a long time under 15%-20% BMCR load, and widening the lower limit of peak shaving.

[0068] 2. Significantly improved climbing performance: Through the dual effects of preheating saturation and thermal pulse, the unit's climbing rate is increased from approximately 1.8% / min to ≥3.5% / min, demonstrating a significant improvement.

[0069] 3. Synergistic environmental protection and energy saving: High-temperature fly ash reinjection creates a local reducing atmosphere, inhibits NOx generation, reduces SCR inlet concentration by 30%-50%, and unburned carbon in fly ash undergoes secondary combustion in the furnace, improving boiler efficiency by about 0.3%-0.5%.

[0070] 4. Excellent investment and operating economy: The main equipment of the system is conventional material conveying equipment with mature technology. The main operating cost is the power consumption of the fan and air compressor. The energy consumption is low, and the fuel auxiliary input is minimal, so the cost is controllable.

[0071] Those skilled in the art will understand that, for ease of explanation, the example is provided with one memory and one processor. In actual terminals or servers, multiple processors and memories may exist. Memory can also be referred to as storage medium or storage device, etc., and the embodiments of this application do not limit this.

[0072] It should be understood that in the embodiments of this application, the processor may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor may also be a general-purpose microprocessor, graphics processing unit (GPU), or one or more integrated circuits to execute relevant programs to achieve the functions required by the embodiments of this application.

[0073] The processor can also be an integrated circuit chip with signal processing capabilities. In implementation, each step of this application can be completed through integrated logic circuits in the processor hardware or instructions in software form. The aforementioned processor can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The steps of the methods disclosed in the embodiments of this application can be directly manifested as execution by a hardware decoding processor, or execution by a combination of hardware and software modules in the decoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the functions required by the units included in the methods, systems, and storage media of the embodiments of this application.

[0074] It should also be understood that the memory mentioned in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory can be random access memory (RAM), which is used as an external cache.

[0075] By way of example, but not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDR SDRAM), Enhanced Synchronous DRAM (ESDRAM), Synchlink DRAM (SLDRAM), and Direct Rambus RAM (DR RAM).

[0076] The memory can also be a Compact Disc Read-Only Memory (CD-ROM) or other optical disc storage, optical disk storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media, or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures that can be accessed by a computer, but is not limited thereto. The memory can exist independently and be connected to the processor via a bus. The memory can also be integrated with the processor. The memory can store programs, and when the program stored in the memory is executed by the processor, the processor performs the various steps of the method determined in the above embodiments of this application.

[0077] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA, or other programmable logic device, discrete gate or transistor logic device, or discrete hardware component, the memory (storage module) is integrated into the processor. It should be noted that the memory described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0078] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0079] In implementation, each step of the above method can be completed by integrated logic circuits in the processor's hardware or by instructions in software. The steps of the method disclosed in the embodiments of this application can be directly implemented by a hardware processor, or by a combination of hardware and software modules within the processor. The software modules can reside in mature storage media in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. Since this storage medium is located in memory, the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method; to avoid repetition, these will not be described in detail here.

[0080] Those skilled in the art will recognize that the various illustrative logical blocks (ILBs) and steps described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this application.

[0081] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer-programmed program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a processor, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a computer network, or other programmable device.

[0082] This embodiment also provides a computer-readable storage medium storing a computer program that causes a computer to execute in order to implement the above-described method based on multi-stage vortex and intelligent feedforward.

[0083] It should be noted that computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic) or wireless (e.g., infrared, wireless, microwave, etc.) means, or from one website, computer, server, or data center to a mobile phone processor via a wired means. A computer-readable storage medium can be any usable medium that a computer can access, or a data storage system such as a server or data center that integrates one or more usable media. Usable media can be magnetic media (e.g., floppy disks, hard disks), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state drives), etc.

[0084] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-temperature internal circulation stable combustion system for fly ash with integrated slope-climbing optimization, characterized in that, include: Fly ash extraction module, fly ash conveying module, fly ash injection module and intelligent control system; The fly ash extraction module is installed in the vertical section of the flue between the boiler economizer and the air preheater, and is used to extract high-temperature fly ash. The fly ash conveying module is connected to the fly ash extraction module and is used to perform gas-solid separation, buffering, and conveying of the extracted fly ash in a dense phase flow state. The fly ash injection module is circumferentially arranged around the furnace wall in the main burner area of ​​the boiler, and is used to evenly inject fly ash into the furnace to form a fly ash curtain covering the burner area. The intelligent control system is communicatively connected to the fly ash extraction module, the conveying and storage module, and the injection module, and includes a basic control layer and a combustion enhancement feedforward control module. The basic control layer is used to adjust the fly ash reinjection flow rate to match the current load according to the boiler load command and real-time combustion signal; The combustion enhancement feedforward control module is used to communicate with the automatic generation control (AGC) system or load forecasting system of the power grid. 60-90 seconds before the boiler load increase coal feeding command is executed, it controls the fly ash reinjection to increase to the peak flow rate and preheats and saturates the combustion zone.

2. The integrated slope-optimized high-temperature internal circulation stable combustion system for fly ash as described in claim 1, characterized in that, The fly ash conveying module includes a cyclone separator, a fly ash buffer bin, a rotary feeder valve, and a dense phase conveying pump. The cyclone separator is used to separate ≥95% of the fly ash and drop it into the fly ash buffer bin. The fly ash buffer bin is equipped with a fluidization device to prevent fly ash caking and maintain stable material level. The rotary feeder valve feeds the fly ash quantitatively into the dense phase conveying pump. The dense phase conveying pump uses compressed air as power to convey the fly ash to the furnace at a solid-gas ratio of 20-40 kg ash / kg air.

3. The integrated slope-optimized high-temperature internal circulation stable combustion system for fly ash as described in claim 1, characterized in that, The fly ash extraction module includes a negative pressure extractor connected to a cyclone separator. The bottom outlet of the cyclone separator is connected to a fly ash buffer chamber. The negative pressure extractor generates negative pressure through a high-pressure fan to extract fly ash and a small amount of flue gas mixed in the flue and then connected to the cyclone separator to achieve preliminary gas-solid separation.

4. The integrated slope-optimized high-temperature internal circulation stable combustion system for fly ash as described in claim 3, characterized in that, The negative pressure extractor includes a venturi tube, a gas supply regulating valve, and a wear-resistant ceramic liner. The end of the negative pressure extractor is provided with an extraction port, and the extraction port is equipped with a grid filter.

5. The integrated slope-optimized high-temperature internal circulation stable combustion system for fly ash as described in claim 4, characterized in that, The fly ash injection module includes multiple adjustable wear-resistant nozzles arranged circumferentially in the furnace burner area. The adjustable wear-resistant nozzles are equipped with swirl vanes inside, which are arranged below or to the side of the secondary air nozzles of the main burner.

6. The integrated slope-optimized high-temperature internal circulation stable combustion system for fly ash as described in claim 1, characterized in that, The adjustable wear-resistant nozzle is connected to an injection pipeline, which is equipped with a pneumatic quick-closing valve and a flow regulating valve for precise control of fly ash injection timing and flow rate.

7. The integrated slope-optimized high-temperature internal circulation stable combustion system for fly ash as described in claim 6, characterized in that, It also includes a fuel auxiliary module, which includes an atomized fuel spray gun, a high-pressure oil / gas supply system, and a fast-acting valve; the fuel auxiliary module is configured to inject a small amount of auxiliary fuel into the furnace to generate a heat pulse during the initial stage of the boiler's rapid load increase process.

8. The integrated slope-optimized high-temperature internal circulation stable combustion system for fly ash as described in claim 1, characterized in that, The intelligent control system is also equipped with a fault alarm module. When the fly ash extraction volume, conveying pressure or injection flow rate deviates from the set threshold by ±10%, an alarm signal is immediately issued and the system switches to manual control mode.

9. A method for stable combustion of fly ash in high-temperature internal circulation with integrated slope-climbing optimization, characterized in that, Includes the following steps: S1, Low-load stable combustion control: When the boiler load is in the range of 15%-20% of the rated load, the fly ash reinjection amount is adjusted through the basic control layer of the intelligent control system. S2, Combustion Enhancement Feedforward Preheating: When the trend of the grid AGC load increase command is detected and the slope is greater than the set value, the combustion enhancement feedforward control module is started 60-90 seconds before the load increase coal feeding command is executed, and the fly ash reinjection amount is increased to the peak flow rate to preheat the combustion zone. S3, Rapid Climbing Coordinated Enhancement: When the load increase coal feeding command is executed, the target climbing rate is analyzed. If the target climbing rate is greater than or equal to the set threshold, a small amount of auxiliary fuel is injected to generate a heat pulse to accelerate the load response. S4, Steady-state recovery: When the load ramp-up rate reaches the target value and the furnace combustion stabilizes, gradually reduce the fly ash reinjection amount to a steady-state value that matches the current load, and stop auxiliary fuel injection.

10. The high-temperature internal circulation stable combustion method for fly ash with integrated slope-climbing optimization as described in claim 9, characterized in that, In step S4, after the load climbs up and stabilizes, the rate of decrease in fly ash reinjection is 0.5-1 t / h.

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