Fly ash treatment system and method for ammonia co-fired power plant

Abstract

Embodiments of the present disclosure provide a fly ash treatment system and method for an ammonia-doped power plant, which comprises a boiler, an electric precipitator, a flow guide conveyor, a reactor and a controller; the reactor is sequentially provided with a preheating desorption zone, an activation capture zone and a cooling stabilization zone along its top-to-bottom direction; high-temperature raw fly ash sequentially passes through the preheating desorption zone for ammonium salt thermal desorption, the activation capture zone for ammonia activation modification and heavy metal capture, and the cooling stabilization zone for cooling treatment under the action of gravity; the activation capture zone is connected with a common ammonia supply system of the power plant for receiving ammonia; the controller is in communication connection with the boiler, the electric precipitator, the flow guide conveyor, the reactor and the common ammonia supply system of the power plant, respectively. The fly ash treatment system and method of the embodiments of the present disclosure can efficiently and on-line treat ammonium salt-containing fly ash generated by ammonia-doped combustion, and simultaneously achieve the synergistic removal and resource utilization of heavy metals in flue gas.

Description

Technical Field

[0001] The embodiments disclosed herein belong to the field of fly ash treatment technology, specifically relating to a fly ash treatment system and method for ammonia co-firing power plants. Background Technology

[0002] Coal-fired power units are transitioning towards low-carbon, flexible, and clean technologies. Ammonia-blended combustion, as a carbon reduction technology, while lowering CO2 emissions, also presents new technical challenges. High-proportion ammonia-blended combustion may lead to the adsorption of ammonium salts (such as ammonium bisulfate) in fly ash, affecting its comprehensive utilization value as a building material resource. Simultaneously, emission standards for heavy metal pollutants such as mercury (Hg) in flue gas from coal-fired power plants are becoming increasingly stringent, and traditional adsorbent injection technologies suffer from high costs, fluctuating efficiency, and poor synergy with ammonia-blended systems.

[0003] In related technologies, the continuous consumption of adsorbents such as activated carbon constitutes a heavy operating cost. Co-treatment schemes utilize fly ash to replace part of the activated carbon, but the treatment process is not economically viable. Furthermore, co-treatment schemes cannot simultaneously achieve real-time response and treatment effectiveness, resulting in high technical complexity and the risk of secondary pollution. Under ammonia-blended combustion conditions, ammonium bisulfate adsorbed on the fly ash surface blocks its pore structure, physically blocking the fly ash's adsorption capacity. Summary of the Invention

[0004] The embodiments disclosed herein aim to at least solve one of the technical problems existing in the prior art, and provide a fly ash treatment system and method for ammonia co-firing power plants.

[0005] On one hand, embodiments of this disclosure provide a fly ash treatment system for an ammonia co-firing power plant, the fly ash treatment system comprising a boiler, an electrostatic precipitator, a diversion conveyor, a reactor, and a controller; The inlet and first outlet of the electrostatic precipitator are respectively connected to the flue gas outlet of the boiler and the inlet of the diversion conveyor. The outlet of the diversion conveyor is connected to the fly ash inlet located at the top of the reactor. The diversion conveyor is used to draw out and transport high-temperature raw fly ash. The reactor is provided with a preheating desorption zone, an activation and collection zone, and a cooling and stabilization zone in sequence from top to bottom. Under the action of gravity, the high-temperature raw fly ash passes through the preheating desorption zone for ammonium salt thermal desorption, the activation and collection zone for ammonia activation modification and heavy metal collection, and the cooling and stabilization zone for cooling treatment. The activation and collection zone is connected to the power plant's public ammonia supply system to receive ammonia. The controller is communicatively connected to the boiler, electrostatic precipitator, diversion conveyor, reactor, and power plant common ammonia supply system. The controller is used to receive boiler load and coal quality analysis signals from the boiler and operating parameter signals from the reactor, and dynamically adjust the electrostatic precipitator, diversion conveyor, reactor, and power plant common ammonia supply system according to the received signals.

[0006] Optionally, the preheating desorption zone is provided with a first heating element for heating the high-temperature raw fly ash to achieve thermal desorption of ammonium salts adsorbed on its surface; the activation and collection zone is provided with a second heating element for controlling the temperature of the activation and collection zone to carry out ammonia activation modification and heavy metal collection of fly ash; the cooling and stabilization zone is provided with a cooling element for cooling the fly ash. The first heating element, the second heating element, and the cooling element are all communicatively connected to the controller.

[0007] Optionally, both the first heating element and the second heating element are heating jackets, and the cooling element is a cooling jacket; the reactor is also equipped with a temperature sensor, which is used to monitor the temperature of each zone in the reactor and transmit the temperature signal to the controller.

[0008] Optionally, the fly ash treatment system further includes an SCR denitrification processor and a chimney; The first inlet and outlet of the SCR denitrification processor are respectively connected to the flue gas outlet of the boiler and the inlet of the electrostatic precipitator, and the inlet of the chimney is connected to the second outlet of the electrostatic precipitator; The reactor is also provided with a tail gas outlet at the top, which is connected to the second inlet of the SCR denitrification processor through a pipeline. This outlet is used to transport the ammonia- and sulfur-containing tail gas generated by the thermal desorption of ammonium salt to the SCR denitrification processor for use as a supplementary reducing agent.

[0009] Optionally, the fly ash treatment system further includes a fly ash silo, the inlet of which is connected to the fly ash outlet located at the bottom of the reactor, for storing the processed functionalized fly ash.

[0010] Optionally, the controller has a built-in algorithm model that can dynamically adjust the temperature setpoints of each zone in the reactor, the ammonia injection rate of the power plant's public ammonia supply system, and the fly ash treatment rate of the diversion conveyor based on real-time received boiler load, coal quality analysis signals, and reactor operating parameters.

[0011] Optionally, the coal quality analysis signal includes a mercury content signal, and the controller uses the standard mercury concentration in the flue gas as a constraint to find the minimum ammonia consumption through an algorithm model and dynamically adjust the corresponding equipment.

[0012] Optionally, the fly ash treatment system enters a standby state during boiler unit startup and when the boiler load is unstable. In the standby state, a small amount of carrier gas is introduced into the reactor through an external gas source to maintain the internal fluidization state, and the power plant's public ammonia supply system remains closed. Once the boiler load stabilizes and the electrostatic precipitator discharges ash normally, the fly ash treatment system enters a steady-state operation mode.

[0013] On the other hand, embodiments of this disclosure also provide a method for treating fly ash in an ammonia-co-firing power plant, characterized in that it is applied to the fly ash treatment system described above, and the fly ash treatment method includes: S1: The system starts up, and the controller instructs the feeder to begin conveying high-temperature raw fly ash into the reactor; S2: Fly ash slowly moves downwards within the reactor due to gravity, sequentially entering the preheating desorption zone, activation and collection zone, and cooling and stabilization zone; among which... In the preheating desorption zone, the ammonium salts adsorbed on the surface of the fly ash are thermally desorbed by heating, thereby purifying the fly ash. In the activation and collection zone, ammonia gas is injected from the power plant's public ammonia supply system to perform in-situ chemical modification on the purified fly ash at a set high temperature, transforming it into a heavy metal adsorbent and simultaneously collecting heavy metals from the flue gas. In the cooling and stabilization zone, the modified functionalized fly ash is cooled and stabilized before being discharged and stored. S3: The controller dynamically adjusts the temperature of each zone of the reactor, the ammonia injection rate, and the fly ash treatment rate based on the real-time received boiler load, coal quality analysis signals, and reactor operating parameters.

[0014] Optionally, in step S3, the controller performs "adaptive optimization" control: with the heavy metal concentration in the flue gas meeting the standard as a constraint, it uses a built-in algorithm model to find the lowest ammonia consumption. When the heavy metal concentration increases, the temperature setpoint and ammonia injection flow rate of the activation collection zone are increased, and the fly ash discharge rate is reduced to prolong its residence time in the activation collection zone; when the heavy metal concentration decreases, the temperature setpoint and ammonia injection flow rate of the activation collection zone are decreased, and the fly ash discharge rate is increased to reduce its residence time in the activation collection zone.

[0015] The fly ash treatment system and method of the ammonia co-firing power plant disclosed herein removes ammonium salts adsorbed on the surface of the fly ash due to ammonia co-firing combustion online before activating the fly ash, thereby improving the adsorption potential. The purified fly ash is converted into a heavy metal adsorbent through in-situ low-cost chemical means, and is integrated with the main system of the power plant to form a circular system without secondary pollution. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a fly ash treatment system for an ammonia co-firing power plant according to an embodiment of the present disclosure. Figure 2 This is a schematic diagram of the structure of a reactor according to an embodiment of the present disclosure. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] like Figure 1 and Figure 2 As shown, embodiments of this disclosure provide a fly ash treatment system for ammonia-blended power plants. This system aims to solve the technical problems of fly ash quality degradation due to ammonium salt adsorption and high cost of removing heavy metals (such as mercury) from flue gas in ammonia-blended power plants, and to achieve online activation of fly ash and synergistic control of pollutants.

[0019] The fly ash treatment system includes a boiler 1, an electrostatic precipitator 2, a diversion conveyor 3, a reactor 4, and a controller 5. The inlet and first outlet of the electrostatic precipitator 2 are connected to the flue gas outlet of the boiler 1 and the inlet of the diversion conveyor 3, respectively. The outlet of the diversion conveyor 3 is connected to the fly ash inlet located at the top of the reactor 4. The diversion conveyor 3 is used to draw out and transport high-temperature raw fly ash. The reactor 4 is provided with a preheating desorption zone 41, an activation and collection zone 42, and a cooling and stabilization zone 43 in sequence from top to bottom. Under the action of gravity, the high-temperature raw fly ash passes through the preheating desorption zone 41 for ammonium salt thermal desorption, the activation and collection zone 42 for ammonia activation modification and heavy metal collection, and the cooling and stabilization zone 43 for cooling treatment. The activation and collection zone 42 is connected to the power plant's public ammonia supply system 6 for receiving ammonia.

[0020] The controller 5 is communicatively connected to the boiler 1, the electrostatic precipitator 2, the diversion conveyor 3, the reactor 4, and the power plant's common ammonia supply system 6. The controller 5 is used to receive boiler load and coal quality analysis signals from the boiler 1 and operating parameter signals from the reactor 4, and dynamically adjust the electrostatic precipitator 2, the diversion conveyor 3, the reactor 4, and the power plant's common ammonia supply system 6 according to the received signals.

[0021] Specifically, such as Figure 1 and Figure 2 As shown, the high-temperature flue gas generated by boiler 1 first enters electrostatic precipitator 2 for dust removal. The high-temperature raw fly ash discharged from electrostatic precipitator 2 is not directly discarded or simply treated, but is instead drawn out in real time from the first outlet of electrostatic precipitator 2 by a diversion conveyor 3 (e.g., a pneumatic conveying pump or screw conveyor) and transported to the subsequent reactor 4 for treatment. This ensures the "online" and "instantaneous" characteristics of fly ash treatment.

[0022] The core equipment is reactor 4, which is designed as a gravity-descending moving bed structure. Fly ash enters from its top inlet and slowly descends naturally under gravity. The interior of reactor 4 is divided into three clearly defined continuous processing zones from top to bottom: Preheating and Desorption Zone 41: Responsible for preheating the fly ash to thermally desorb ammonium salts such as ammonium bisulfate adsorbed on its surface. Activation and Collection Zone 42: In this zone, ammonia gas is injected through the power plant's public ammonia supply system 6 to chemically modify the purified fly ash at a suitable temperature, transforming it into functionalized fly ash with heavy metal adsorption capacity, while simultaneously collecting heavy metals. Cooling and Stabilization Zone 43: The modified fly ash is cooled to ensure its stable properties for easy storage.

[0023] The intelligent operation of the entire system is coordinated by Controller 5 (i.e., the intelligent control system). Controller 5 is communicatively connected to the boiler DCS, electrostatic precipitator, diversion conveyor, reactor, and various heating / cooling components and ammonia supply system. It receives real-time operating parameters such as boiler load (reflecting flue gas flow), coal quality analysis signals (especially mercury content, reflecting pollutant load), and reactor temperature and pressure, and dynamically and collaboratively regulates the operating status of each device in the entire system to achieve adaptive and optimized operation.

[0024] For example, such as Figure 2 As shown, the preheating desorption zone 41 is equipped with a first heating element 411 for heating the high-temperature raw fly ash to achieve thermal desorption of ammonium salts adsorbed on its surface; the activation and collection zone 42 is equipped with a second heating element 421 for controlling the temperature of the activation and collection zone to carry out ammonia activation modification and heavy metal collection of fly ash; the cooling and stabilization zone 43 is equipped with a cooling element 431 for cooling the fly ash; the first heating element 411, the second heating element 421 and the cooling element 431 are all communicatively connected to the controller 5.

[0025] Specifically, to achieve precise temperature control in the three functional zones, reactor 4 is equipped with dedicated heating and cooling components, which are linked to controller 5. In the preheating desorption zone 41, a first heating element 411 is installed, such as a heating jacket surrounding the zone. Controller 5 instructs this heating element to control the zone temperature within, for example, a range of 200-300°C, according to a preset program or real-time operating conditions. At this temperature, ammonium salts (such as NH4HSO4) adsorbed on the fly ash surface undergo efficient thermal decomposition (NH4HSO4 → NH3↑ + SOx↑), releasing NH3 and SOx gases that become usable tail gas, purifying the fly ash itself and "unlocking" its pores.

[0026] In the activation and collection zone 42, a separate second heating element 421 is installed, such as another heating jacket or a built-in electric heater. The controller 5 instructs it to maintain the temperature within a higher activation temperature range (e.g., 300-450°C). At this temperature, ammonia gas from the power plant's public ammonia supply system 6 can undergo an effective surface chemical reaction with the purified fly ash, generating active sites and transforming it into a highly efficient heavy metal adsorbent. In the cooling and stabilization zone 43, a cooling element 431, such as a cooling jacket, is installed, through which circulating water or air is introduced to cool the high-temperature functionalized fly ash, reducing its temperature to a safe storage range (e.g., below 80°C). All these heating and cooling elements are communicatively connected to the controller 5 and subject to its unified scheduling, ensuring precise and stable temperatures in the three zones to meet the needs of different processing stages.

[0027] The first and second heating elements are preferably in the form of heating jackets, i.e., jacket structures surrounding the outer wall of the corresponding areas of reactor 4, through which a heat medium (such as steam or electric heating) can be introduced. The cooling element is also preferably in the form of a cooling jacket, through which a cooling medium is introduced. This design facilitates maintenance and provides uniform temperature control. Furthermore, to achieve precise closed-loop temperature control, temperature sensors (not shown), such as multiple distributed thermocouples or resistance temperature detectors (RTDs), are installed inside reactor 4. These sensors monitor the actual temperatures of the preheating desorption zone 41, the activation and trapping zone 42, and the cooling stabilization zone 43 in real time and continuously feed the signals back to the controller 5. The controller 5 dynamically adjusts the power (such as steam flow rate or current) of the heating or cooling jacket based on the difference between the set temperature and the measured temperature, forming a stable temperature control loop.

[0028] For example, such as Figure 1 As shown, the fly ash treatment system also includes an SCR denitrification processor 7 and a chimney 8; the first inlet and outlet of the SCR denitrification processor 7 are respectively connected to the flue gas outlet of the boiler 1 and the inlet of the electrostatic precipitator 2, and the inlet of the chimney 8 is connected to the second outlet of the electrostatic precipitator 2; the top of the reactor 4 is also provided with a tail gas outlet, which is connected to the second inlet of the SCR denitrification processor 7 through a pipeline, for transporting the ammonia-containing and sulfur-containing tail gas generated by the thermal desorption of ammonium salt to the SCR denitrification processor 7 for use as a supplementary reducing agent.

[0029] Specifically, the embodiments of this disclosure achieve closed-loop recycling and resource utilization of pollutants. The system also includes a conventional SCR denitrification system 7 and a chimney 8. The treated flue gas is ultimately discharged through the chimney 8. The key design feature is that a tail gas outlet is provided at the top of the reactor 4. The tail gas rich in NH3 and SOx generated in the preheating desorption zone 41 is discharged through this outlet. This tail gas is transported back to the second inlet of the SCR denitrification system 7 through a dedicated pipeline. In this way, the NH3 in the tail gas can be directly utilized as a supplementary reducing agent for the SCR denitrification reaction, reducing the consumption of external ammonia; while the SOx in the tail gas can be treated in the subsequent desulfurization system along with the main flue gas. This design achieves internal recycling of the by-products (NH3, SOx) generated during the treatment process, greatly reducing secondary pollution and improving the material utilization efficiency and environmental friendliness of the entire power plant system.

[0030] For example, such as Figure 1 and Figure 2 As shown, the fly ash treatment system also includes a fly ash silo 9, the inlet of which is connected to the fly ash outlet located at the bottom of the reactor 4, for storing the processed functionalized fly ash.

[0031] To store the processed product, the system also includes a fly ash silo 9 (i.e., a functionalized fly ash silo). The inlet of fly ash silo 9 is connected to the fly ash outlet at the bottom of reactor 4 via a conveying device (such as a screw conveyor). After preheating desorption, activation collection, and cooling stabilization, the functionalized fly ash is discharged from the bottom of reactor 4 and directly enters fly ash silo 9 for storage. This functionalized fly ash, modified with ammonia, has high adsorption activity for heavy metals (such as mercury). It can be reused as a high-quality adsorbent for flue gas purification (e.g., injected into flue gas ducts for deep mercury removal) or used as a building material raw material with improved properties for comprehensive utilization, truly realizing "turning waste into treasure".

[0032] For example, the controller has a built-in algorithm model that can dynamically adjust the temperature setpoint of each zone in the reactor 4, the ammonia injection rate of the power plant public ammonia supply system 6, and the fly ash treatment rate of the diversion conveyor 3 based on the real-time received boiler load, coal quality analysis signals, and reactor operating parameters.

[0033] The controller 5 has pre-built or online learning algorithms (such as optimized models based on reaction kinetics, heat and mass transfer models, or empirical data). This model takes real-time received multi-dimensional signals as input. Boiler load signal: reflects flue gas flow and system processing load.

[0034] Coal quality analysis signals, especially the content of key heavy metals (such as mercury), directly determine the required fly ash activation / adsorption capacity.

[0035] Reactor operating parameters: such as temperature, pressure, and fly ash level in each zone.

[0036] Based on these inputs, the algorithm model calculates and outputs the optimal control command online, dynamically adjusting three key variables: Temperature settings for each zone of reactor 4: Adjust the target temperatures of the preheating desorption zone 41, the activation and collection zone 42, and the cooling and stabilization zone 43 to optimize desorption efficiency and activation effect.

[0037] Ammonia injection rate of power plant public ammonia supply system 6: Precisely control the flow rate of ammonia participating in the activation reaction to avoid waste.

[0038] The fly ash treatment rate of the diversion conveyor 3: Adjusting the fly ash flow rate into the reactor 4 changes the residence time of fly ash in each functional zone, thus affecting the treatment depth.

[0039] This model-based feedforward and feedback composite control enables the system to respond in advance to changes in coal quality and adjust in real time to maintain optimal processing efficiency and economy.

[0040] Furthermore, the coal quality analysis signal includes a mercury content signal, and the controller 5 uses the standard mercury concentration in the flue gas as a constraint to find the minimum ammonia consumption through an algorithm model and dynamically adjust the corresponding equipment.

[0041] Specifically, the algorithm model operates an "adaptive optimization" control strategy in an optimized implementation mode. This strategy uses the final environmental indicator—meeting the standard for mercury concentration in flue gas—as a rigid constraint. Controller 5 acquires mercury concentration data in real time, and its built-in optimization algorithm (such as gradient descent or genetic algorithm) aims to find and maintain the lowest ammonia consumption in the system while ensuring the mercury concentration meets the standard, thus achieving optimal economic efficiency. The specific optimization adjustment logic is as follows: When a mercury concentration rises or exceeds the warning threshold, the algorithm determines that the current activation conditions are insufficient and the fly ash adsorption capacity may not be keeping up with the pollutant load. It immediately issues adjustment commands: increasing the temperature setpoint of the activation collection zone 42 (enhancing the activation reaction intensity), increasing the ammonia injection flow rate (providing more reaction raw materials), and decreasing the fly ash discharge rate (i.e., extending the residence time of fly ash in the activation zone for more complete modification). These three factors work synergistically to rapidly improve the system's heavy metal removal capacity.

[0042] When the mercury concentration is monitored to be stable, within acceptable limits, and at a low level, the algorithm determines that the system's processing capacity has a margin of error. To save costs, it will perform reverse fine-tuning: appropriately lowering the activation zone temperature, reducing ammonia injection, and increasing the fly ash processing rate (i.e., increasing output). This process continues until the lowest operating cost point that meets the compliance constraints is found.

[0043] Furthermore, the fly ash treatment system enters a standby state during boiler unit startup and when the boiler load is unstable. In the standby state, a small amount of carrier gas is introduced into the reactor through an external gas source to maintain the internal fluidization state, and the power plant's public ammonia supply system remains closed. Once the boiler load stabilizes and the electrostatic precipitator discharges ash normally, the fly ash treatment system switches to a steady-state operation mode.

[0044] To adapt to the fluctuations in actual power plant operation, this system is designed with a flexible operating mode switching mechanism. During unstable phases such as boiler unit startup, severe load fluctuations, or low-load operation, the ash discharge from electrostatic precipitator 2 is low or irregular. At this time, the system does not completely shut down but enters standby mode. In standby mode: fly ash treatment is suspended, the fly ash conveyor 3 stops conveying fly ash, and the ammonia supply system 6 is shut down. The reactor maintains its basic state, and to prevent internal ash accumulation or equipment cooling, an external air source (such as...) is used... Figure 2 (412) A small amount of carrier gas (such as nitrogen or air) is introduced into reactor 4 to maintain a slight fluidization or purging state inside the equipment. Controller 5 instructs the first and second heating elements to maintain a low standby temperature (such as 150°C) to prepare for rapid start-up.

[0045] Once the boiler load stabilizes and the electrostatic precipitator 2 begins normal and continuous ash discharge, the controller 5 receives a stable operation signal from the power plant's main DCS and automatically instructs the system to switch from standby mode to steady-state operation mode, initiating normal online fly ash treatment according to the aforementioned process. This design ensures the system's rapid response and continuous operation capability.

[0046] The fly ash treatment system of the ammonia co-firing power plant disclosed in this embodiment can remove ammonium salts adsorbed on the surface of fly ash due to ammonia co-firing before activation, thereby improving the adsorption potential. It can also convert the purified fly ash into a heavy metal adsorbent through in-situ low-cost chemical means and integrate it with the main system of the power plant to form a circular system without secondary pollution.

[0047] On the other hand, embodiments of this disclosure also provide a method for treating fly ash in an ammonia-co-firing power plant, applied to the fly ash treatment system described above. The specific structure of the fly ash treatment system is described in the preceding text and will not be repeated here. The fly ash treatment method includes: S1: The system starts up, and the controller instructs the feeder to begin conveying high-temperature raw fly ash into the reactor; S2: Fly ash slowly moves downwards within the reactor due to gravity, sequentially entering the preheating desorption zone, activation and collection zone, and cooling and stabilization zone; among which... In the preheating desorption zone, the ammonium salts adsorbed on the surface of the fly ash are thermally desorbed by heating, thereby purifying the fly ash. In the activation and collection zone, ammonia gas is injected from the power plant's public ammonia supply system to perform in-situ chemical modification on the purified fly ash at a set high temperature, transforming it into a heavy metal adsorbent and simultaneously collecting heavy metals from the flue gas. In the cooling and stabilization zone, the modified functionalized fly ash is cooled and stabilized before being discharged and stored. S3: The controller dynamically adjusts the temperature of each zone of the reactor, the ammonia injection rate, and the fly ash treatment rate based on the real-time received boiler load, coal quality analysis signals, and reactor operating parameters.

[0048] See attached document Figure 1 and 2 The specific process is as follows: S1: System Start-up and Feeding. When the power plant enters a stable operating condition, the controller 5 instructs the feeder 3 to start, continuously conveying the high-temperature raw fly ash collected by the electrostatic precipitator 2 to the top of the reactor 4.

[0049] S2: Fly ash cascade treatment. The fly ash falls slowly under gravity within reactor 4, undergoing the following processes sequentially: In the preheating desorption zone 41: the fly ash is heated by the first heating element 411, causing the ammonium salts on the fly ash surface to desorb thermally, and the fly ash is purified.

[0050] In the activation and collection zone 42, ammonia gas is injected by the ammonia supply system 6. Under the high temperature maintained by the second heating element 421, the purified fly ash is chemically modified to become a heavy metal adsorbent, and heavy metals are adsorbed simultaneously in the process.

[0051] In the cooling stabilization zone 43: the temperature is reduced by the cooling element 431 to obtain a stable functionalized fly ash product, which is then discharged and stored.

[0052] S3: Intelligent Dynamic Control. Throughout the process, controller 5 dynamically adjusts the three key process variables mentioned in S2—temperature in each zone, ammonia injection rate, and fly ash treatment rate—based on real-time received boiler load, coal quality (mercury content) signals, and reactor parameters, to ensure optimal treatment results and most economical operation.

[0053] Further, in step S3, the controller 5 performs "adaptive optimization" control: with the heavy metal concentration in the flue gas meeting the standard as a constraint, it uses a built-in algorithm model to find the lowest ammonia consumption; when the heavy metal concentration increases, it increases the temperature setpoint of the activation collection zone 42 and the ammonia injection flow rate, and reduces the fly ash discharge rate to prolong its residence time in the activation collection zone 42; when the heavy metal concentration decreases, it decreases the temperature setpoint of the activation collection zone 42 and the ammonia injection flow rate, and increases the fly ash discharge rate to reduce its residence time in the activation collection zone 42.

[0054] Specifically, the goal is to find the lowest ammonia consumption while ensuring that the concentration of heavy metals (taking mercury as an example) in the flue gas meets the standard. Inputs and constraints: The mercury concentration data in the flue gas is the core constraint. Adjustment actions: When the heavy metal concentration increases, the system determines that the processing capacity needs to be enhanced. The adjustment strategy is "three increases and one decrease": increasing the temperature setpoint of the activation and collection zone (heating), increasing the ammonia injection flow rate (feeding), and decreasing the fly ash discharge rate (i.e., extending the residence time of fly ash in the activation zone). These three factors work together to rapidly improve the activation level of the fly ash and the adsorption capacity of individual particles.

[0055] When the heavy metal concentration decreases and stabilizes at a low level, the system determines that resources can be saved. The adjustment strategy is a reverse "three reductions and one increase": reduce the activation zone temperature, reduce the ammonia injection rate, and increase the fly ash discharge rate (i.e., shorten the residence time). Operating costs are reduced as much as possible while meeting the standards. Through this continuous adaptive optimization, the system can intelligently respond to changes in coal quality and load, always maintaining the optimal operating point of "meeting the standards and minimizing costs."

[0056] The fly ash treatment method for ammonia-blended power plants disclosed in this invention integrates fly ash ammonium salt desorption, ammonia activation and modification, heavy metal synergistic capture, intelligent optimization control, and by-product recycling into an online, continuous process. This effectively solves the synergistic problem of fly ash resource utilization and deep mercury removal in ammonia-blended power plants, and has significant technological advancement and economic and environmental value.

[0057] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A fly ash treatment system for an ammonia co-firing power plant, characterized in that, The fly ash treatment system includes a boiler, an electrostatic precipitator, a diversion conveyor, a reactor, and a controller; The inlet and first outlet of the electrostatic precipitator are respectively connected to the flue gas outlet of the boiler and the inlet of the diversion conveyor. The outlet of the diversion conveyor is connected to the fly ash inlet located at the top of the reactor. The diversion conveyor is used to draw out and transport high-temperature raw fly ash. The reactor is provided with a preheating desorption zone, an activation and collection zone, and a cooling and stabilization zone in sequence from top to bottom. Under the action of gravity, the high-temperature raw fly ash passes through the preheating desorption zone for ammonium salt thermal desorption, the activation and collection zone for ammonia activation modification and heavy metal collection, and the cooling and stabilization zone for cooling treatment. The activation and collection zone is connected to the power plant's public ammonia supply system to receive ammonia. The controller is communicatively connected to the boiler, electrostatic precipitator, diversion conveyor, reactor, and power plant common ammonia supply system. The controller is used to receive boiler load and coal quality analysis signals from the boiler and operating parameter signals from the reactor, and dynamically adjust the electrostatic precipitator, diversion conveyor, reactor, and power plant common ammonia supply system according to the received signals.

2. The fly ash treatment system for ammonia co-firing power plants according to claim 1, characterized in that, The preheating desorption zone is equipped with a first heating element for heating the high-temperature raw fly ash to achieve thermal desorption of ammonium salts adsorbed on its surface; the activation and collection zone is equipped with a second heating element for controlling the temperature of the activation and collection zone to carry out ammonia activation modification and heavy metal collection of fly ash; the cooling and stabilization zone is equipped with a cooling element for cooling the fly ash. The first heating element, the second heating element, and the cooling element are all communicatively connected to the controller.

3. The fly ash treatment system for ammonia co-firing power plants according to claim 2, characterized in that, The first heating element and the second heating element are both heating jackets, and the cooling element is a cooling jacket; the reactor is also equipped with a temperature sensor, which is used to monitor the temperature of each zone in the reactor and transmit the temperature signal to the controller.

4. The fly ash treatment system for ammonia co-firing power plants according to claim 1, characterized in that, The fly ash treatment system also includes an SCR denitrification processor and a chimney; The first inlet and outlet of the SCR denitrification processor are respectively connected to the flue gas outlet of the boiler and the inlet of the electrostatic precipitator, and the inlet of the chimney is connected to the second outlet of the electrostatic precipitator; The reactor is also provided with a tail gas outlet at the top, which is connected to the second inlet of the SCR denitrification processor through a pipeline. This outlet is used to transport the ammonia- and sulfur-containing tail gas generated by the thermal desorption of ammonium salt to the SCR denitrification processor for use as a supplementary reducing agent.

5. The fly ash treatment system for ammonia co-firing power plants according to any one of claims 1 to 4, characterized in that, The fly ash treatment system also includes a fly ash silo, the inlet of which is connected to the fly ash outlet located at the bottom of the reactor, for storing the processed functionalized fly ash.

6. The fly ash treatment system for an ammonia co-firing power plant according to any one of claims 1 to 4, characterized in that, The controller has a built-in algorithm model that can dynamically adjust the temperature setpoints of each zone in the reactor, the ammonia injection rate of the power plant's public ammonia supply system, and the fly ash treatment rate of the diversion conveyor based on real-time received boiler load, coal quality analysis signals, and reactor operating parameters.

7. The fly ash treatment system for ammonia co-firing power plants according to claim 6, characterized in that, The coal quality analysis signal includes a mercury content signal. The controller uses the requirement that the mercury concentration in the flue gas meets the standard as a constraint, and uses an algorithm model to find the minimum ammonia consumption and dynamically adjust the corresponding equipment.

8. The fly ash treatment system for ammonia co-firing power plants according to claim 1, characterized in that, The fly ash treatment system enters standby mode during boiler unit startup and when the boiler load is unstable. In standby mode, a small amount of carrier gas is introduced into the reactor through an external gas source to maintain the internal fluidization state, and the power plant's public ammonia supply system remains closed. Once the boiler load stabilizes and the electrostatic precipitator discharges ash normally, the fly ash treatment system enters steady-state operation mode.

9. A method for treating fly ash from an ammonia-co-firing power plant, characterized in that, The fly ash treatment method, applied to the fly ash treatment system according to any one of claims 1 to 8, comprises: S1: The system starts up, and the controller instructs the feeder to begin conveying high-temperature raw fly ash into the reactor; S2: Fly ash slowly moves downwards within the reactor due to gravity, sequentially entering the preheating desorption zone, activation and collection zone, and cooling and stabilization zone; among which... In the preheating desorption zone, the ammonium salts adsorbed on the surface of the fly ash are thermally desorbed by heating, thereby purifying the fly ash. In the activation and collection zone, ammonia gas is injected from the power plant's public ammonia supply system to perform in-situ chemical modification on the purified fly ash at a set high temperature, transforming it into a heavy metal adsorbent and simultaneously collecting heavy metals from the flue gas. In the cooling and stabilization zone, the modified functionalized fly ash is cooled and stabilized before being discharged and stored. S3: The controller dynamically adjusts the temperature of each zone of the reactor, the ammonia injection rate, and the fly ash treatment rate based on the real-time received boiler load, coal quality analysis signals, and reactor operating parameters.

10. The fly ash treatment method according to claim 9, characterized in that, In step S3, the controller performs "adaptive optimization" control: with the heavy metal concentration in the flue gas meeting the standard as a constraint, it uses a built-in algorithm model to find the lowest ammonia consumption. When the concentration of heavy metals increases, the temperature setpoint and ammonia injection flow rate of the activation collection zone are increased, and the fly ash discharge rate is reduced to prolong its residence time in the activation collection zone. When the heavy metal concentration decreases, reduce the temperature setpoint and ammonia injection flow rate of the activation collection zone, and increase the fly ash discharge rate to reduce its residence time in the activation collection zone.

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