Waste incineration flue gas deacidification system and method based on fly ash slurry intelligent back spraying

Abstract

The application discloses a kind of based on fly ash slurry intelligent back spray waste incineration flue gas deacidification system and method, it is related to solid waste treatment and flue gas purification technical field, the waste incineration flue gas deacidification system includes pre-solution tank, water washing tank and pulp tank, pre-solution tank is equipped with fly ash inlet, fly ash inlet is used to connect ash bin, the inside bottom side of pre-solution tank is equipped with aeration pipeline, the top of pre-solution tank is equipped with waste gas discharge port;The inlet of water washing tank is connected with the outlet of pre-solution tank, the outlet of water washing tank is connected to the inlet of solid-liquid separation device, the filtrate outlet of solid-liquid separation device is connected to waste water tank, the solid discharge port of solid-liquid separation device is connected with the inlet of pulp tank, the outlet of pulp tank is used to be connected to the temperature reducing water inlet of rotary atomizer in the top of SDA tower by slurry pump.The application can solve the problem of back spray secondary pollution, and the problem of poor economy of fixed proportion addition and easy to exceed standard under fluctuating conditions.

Description

Technical Field

[0001] This invention relates to the field of solid waste treatment and flue gas purification technology, and in particular to a waste incineration flue gas deacidification system and method based on intelligent fly ash sludge reinjection. Background Technology

[0002] Waste incineration flue gas contains acidic pollutants such as HCl and SO2, which are typically purified using a spray drying deacidification tower (SDA) that injects slaked lime slurry combined with a bag filter. This process generates a large amount of fly ash rich in unreacted slaked lime (Ca(OH)2) and reaction products (CaCl2, CaSO3, etc.). Currently, fly ash is treated as hazardous waste, resulting in high disposal costs; simultaneously, the consumption of fresh slaked lime is one of the main operating costs of flue gas treatment.

[0003] Invention patent CN115779648B proposes a device and method for recycling fly ash from waste incineration for semi-dry flue gas desulfurization. The hardware scheme involves collecting fly ash from the desulfurization tower and dust collector, feeding it into a grinder, and directly adding fresh slaked lime powder during the grinding process to produce a "fly ash-slaked lime composite powder." Water is then added to make a slurry, which is finally mixed with pure slaked lime slurry at a fixed ratio (e.g., 1:9 to 2:8) and sprayed back into the desulfurization tower. While this technology achieves fly ash reuse, it has the following significant drawbacks: (1) No water washing, dechlorination and ammonia removal were performed, which poses a secondary pollution risk and equipment hazard.

[0004] This technology directly mixes and grinds raw fly ash with lime to form a slurry. Raw fly ash contains a large amount of soluble chloride salts (15-30%) and ammonium salts generated in the furnace. Direct re-injection will lead to: a) chloride ions accumulating in the deacidification ash, increasing the difficulty of subsequent fly ash disposal; b) ammonium salts decomposing to generate ammonia gas at high temperatures in the SDA tower, resulting in excessive ammonia escape from the flue gas.

[0005] (2) Using a fixed ratio for addition cannot adapt to dynamic working conditions (extensive control).

[0006] The technology explicitly proposes "mixing fly ash slurry and hydrated lime slurry at a fixed mass ratio of 0.5:9.5 to 3:7". However, the concentration of flue gas from waste incineration varies rapidly, and a fixed ratio cannot achieve the economically optimal state of "using as little new lime as possible".

[0007] (3) The difference in reaction kinetics between “pure fly ash slurry” and “lime slurry” was not identified.

[0008] This technology does not use pure fly ash for pulping; instead, it premixes lime. Pure fly ash slurry (without premixed lime) has a much lower reactivity than fresh lime because its surface is coated with reaction products. Directly applying conventional deacidification PID algorithms would lead to severe computational distortion and control lag.

[0009] Invention patent application CN121130640A proposes a treatment system and method for co-purifying flue gas with fly ash washing liquid from waste incineration. The system involves washing and desalting the fly ash to obtain a washing liquid, which is then concentrated in a wet scrubbing tower. Finally, the concentrated liquid is sent to a semi-dry desulfurization tower for atomization and evaporation. This technology focuses on zero-discharge treatment of the washing waste liquid and does not address the intelligent and precise control of the dosage of deacidifying agents. Summary of the Invention

[0010] The purpose of this invention is to provide a waste incineration flue gas deacidification system and method based on intelligent fly ash slurry reinjection, so as to at least partially solve the above-mentioned technical problems.

[0011] To address the aforementioned technical problems, the embodiments of the present invention provide the following technical solutions: On one hand, embodiments of the present invention provide a waste incineration flue gas deacidification system based on intelligent fly ash sludge reinjection, comprising a pre-dissolving tank for pre-washing ammonia removal, a washing tank for water washing dechlorination, and a pulping tank for pulping, wherein: The pre-dissolving tank is provided with a process water inlet and a fly ash inlet. The fly ash inlet is used to connect to the ash silo. An aeration pipe is provided on the bottom side of the interior of the pre-dissolving tank. A sealed top cover is provided on the top of the pre-dissolving tank. An exhaust port is provided on the sealed top cover. The inlet of the washing tank is connected to the outlet of the pre-dissolving tank, the outlet of the washing tank is connected to the inlet of the solid-liquid separation device, and the filtrate outlet of the solid-liquid separation device is connected to the wastewater tank through a pipeline. The solid discharge port of the solid-liquid separation device is connected to the inlet of the slurry tank, and the outlet of the slurry tank is connected to the desuperheating water inlet of the rotary atomizer at the top of the SDA tower via a mud pump.

[0012] On the other hand, embodiments of the present invention provide a method for desulfurizing flue gas from waste incineration, utilizing the aforementioned waste incineration flue gas desulfurization system based on intelligent fly ash sludge reinjection, comprising: Step S1, Fly ash washing and pulping: Collect fly ash and send it into a pre-dissolving tank, add water and stir and aerate at the bottom. The generated ammonia-containing waste gas is pumped to the waste gas treatment system. The pre-washed slurry is dechlorinated by a solid-liquid separation device, and the desalted sludge is sent into a pulping tank and water is added to prepare fly ash slurry. Step S2, Real-time Acquisition of Multi-Source Data: Real-time acquisition of flue gas flow rate and acid gas concentration at the SDA tower inlet, acid gas concentration in the net flue gas at the outlet, and the real-time effective alkalinity A of fly ash slurry in the slurry mixing tank. slurry ; Step S3: Dynamic Calculation and Nonlinear Dynamic Allocation of Total Caustic Soda Demand: Based on the inlet flue gas parameters, the feedforward caustic soda demand is calculated using a feedforward model; based on the outlet flue gas parameters, the feedback correction caustic soda demand is calculated using a feedback model; and the weighted fusion yields the total caustic soda demand M at the current moment. total The maximum amount of alkali that the mud can provide is calculated, and the mud flow rate command is output through nonlinear distribution logic to ensure that the mud flow rate approaches the maximum safe flow rate as demand increases, and the remaining gap is accurately replenished by fresh lime slurry. Step S4, Execution and Closed Loop: The mud flow command and lime slurry flow command obtained in step S3 are sent to the corresponding regulating valves and variable frequency pumps for execution, and the clean flue gas concentration is continuously monitored to form a closed loop.

[0013] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: The waste incineration flue gas deacidification system and method based on intelligent fly ash slurry reinjection in this invention can utilize unreacted quicklime in waste incineration fly ash to assist in deacidification, and optimize the consumption of fresh quicklime through intelligent regulation. The waste incineration flue gas deacidification system has aeration to remove ammonia and water washing to remove chlorine, solving the problem of secondary pollution from reinjection. The waste incineration flue gas deacidification method establishes an online monitoring mechanism for slurry alkalinity, eliminating the "blind spot" of the control system. At the same time, based on the feedforward-feedback composite control algorithm for real-time dynamic correction of slurry alkalinity and the "slurry priority fallback" allocation logic, it completely solves the problems of poor economy of fixed-ratio addition and easy exceedance under fluctuating operating conditions. Attached Figure Description

[0014] The accompanying drawings in this application are intended to supplement the textual description in the specification with graphics, and to further explain the technical solution of this application. They do not constitute an undue limitation on this application.

[0015] Figure 1 This is a schematic diagram of the waste incineration flue gas deacidification system based on intelligent fly ash sludge reinjection according to the present invention. Figure 2 This is a schematic diagram of the process for the waste incineration flue gas deacidification method based on intelligent fly ash sludge reinjection according to the present invention. Figure 3 This is a schematic diagram of the waste incineration flue gas deacidification method based on intelligent fly ash slurry reinjection according to the present invention. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0017] In the description of this invention, it should be understood that the terms "center," "lateral," "longitudinal," "front," "rear," "left," "right," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0018] Terminology Explanation: Fly ash: refers to the fly ash collected by the flue gas purification system in a waste incineration line.

[0019] SDA tower: Spray drying semi-dry deacidification tower, is the main equipment for deacidification.

[0020] Rotary atomizing sprayer: Installed at the top of the SDA tower, it is a core and key device that atomizes the slurry through high-speed rotation and centrifugal force.

[0021] Effective alkalinity: refers to the content of alkaline substances (calculated as Ca(OH)2) in the slurry that can actually participate in the neutralization reaction of acidic gases (HCl, SO2, etc.).

[0022] To address the shortcomings of existing fly ash recycling systems, such as easy equipment clogging, incomplete impurity removal, inability to detect sludge alkalinity fluctuations, and crude control logic leading to lime waste or excessive emissions, the technical problems to be solved by this invention include: (1) How to efficiently remove ammonia and chloride salts from fly ash slurry through optimized water washing pulping hardware structure, and prevent secondary pollution and equipment scaling when spraying back to the SDA tower; (2) How to accurately sense the effective alkalinity of fly ash slurry with drastic fluctuations and use this as a basis for dynamic feedforward control; (3) How to establish an intelligent allocation logic of "maximizing the utilization of mud and accurately filling the gap with new lime" under the premise of meeting strict environmental protection standards, so as to minimize economic costs.

[0023] This invention relates to a flue gas purification system and method that utilizes unreacted quicklime from waste incineration fly ash to assist in acid removal and optimizes the consumption of fresh quicklime through intelligent control. The objectives include: Hardware objective: To provide a dedicated pulping system with aeration for ammonia removal and water washing for dechlorination, thus solving the problem of secondary pollution from backflow.

[0024] Objective: To establish an online monitoring mechanism for mud alkalinity and eliminate "blind spots" in the control system.

[0025] Control Objective: To propose a feedforward-feedback composite control algorithm based on real-time dynamic correction of mud alkalinity and a "mud priority catch-up" allocation logic, so as to completely solve the problems of poor economy of fixed-ratio addition and easy exceedance under fluctuating conditions.

[0026] On the one hand, embodiments of the present invention provide a waste incineration flue gas deacidification system based on intelligent fly ash sludge reinjection, which has ammonia removal and dechlorination functions, such as... Figure 1 As shown, it includes a pre-dissolving tank 1 for pre-washing and ammonia removal, a washing tank 2 for water washing and dechlorination, and a pulping tank 3 for pulping, wherein: The pre-dissolving tank 1 is equipped with a process water inlet (specifically located at the lower part of the side wall of the pre-dissolving tank 1) and a fly ash inlet. The fly ash inlet is used to connect to the (fly) ash silo 4. Specifically, the bottom of the ash silo 4 can be connected to a pneumatic conveying pipeline through a variable frequency rotary valve. The outlet of the pneumatic conveying pipeline extends into the top of the pre-dissolving tank 1, thereby realizing fly ash collection and conveying. The bottom of the pre-dissolving tank 1 is equipped with an aeration pipe. Specifically, the aeration pipe can be a ring-shaped microporous aeration pipe and is set horizontally. At the same time, the aeration pipe can be connected to a Roots blower through a pipeline. The top of the pre-dissolving tank 1 is equipped with a sealed top cover, and the sealed top cover is equipped with an exhaust port. Specifically, the exhaust port is used to connect to the front-end quench tower or pickling exhaust gas treatment system of the plant through an exhaust fan and pipeline. Understandably, the pre-dissolving tank 1 and related structures (aeration pipes, exhaust gas blowers, etc.) constitute a pre-washing ammonia removal system. Its function is to introduce aeration air during water washing to convert the ammonium salts in the fly ash into ammonia gas and extract it away, preventing ammonia escape caused by subsequent back spraying.

[0027] The inlet of the washing tank 2 is connected to the outlet of the pre-dissolving tank 1. Specifically, the pre-dissolving tank 1 can be arranged above the washing tank 2. The bottom of the pre-dissolving tank 1 is connected to the top of the washing tank 2 through a pipe. The pre-dissolving slurry enters the washing tank 2 by gravity for washing. The outlet of the washing tank 2 is connected to the inlet of the solid-liquid separation device. The filtrate outlet of the solid-liquid separation device is connected to the wastewater tank 5 through a pipeline. Specifically, the bottom of the washing tank 2 can be equipped with a transfer pump to transport the washing liquid to the inlet of the solid-liquid separation device. The solid-liquid separation device can be of various structural forms in the art, such as a hydrocyclone and a plate and frame filter press connected in sequence, or a horizontal centrifuge 6 as shown in the figure. The wastewater outlet of the wastewater tank 5 can be connected to the pre-dissolving tank 1 and the washing tank 2 through a transfer pump to reuse the wastewater, and the other path can be connected to the evaporation and salt separation system 7 to concentrate the salt and then evaporate and separate it. The structure of the evaporation and salt separation system 7 is common knowledge in the art and will not be described in detail here. Understandably, the water washing tank 2 and the solid-liquid separation device together constitute a water washing dechlorination and separation system.

[0028] The solid discharge port of the solid-liquid separation device is connected to the inlet of the slurry tank 3. The outlet of the slurry tank 3 (specifically, the bottom outlet) is connected to the desuperheating water (loop pipe) inlet of the rotary atomizer 8 at the top of the SDA tower via a (variable frequency) mud pump. An electromagnetic flow meter and an electric regulating valve can be installed on the outlet pipe of this mud pump for flow control. It should be noted that the main inlet of the rotary atomizer 8 is not connected here; instead, a desuperheating water interface is used. This allows for secondary mud crushing using the centrifugal force of high-speed rotation, preventing large fly ash particles from clogging the main nozzle.

[0029] Understandably, the pulping tank 3 and the rotary atomizer 8 together constitute the pulping and reflow system.

[0030] In some embodiments of the present invention, both the pre-dissolving tank 1 and the washing tank 2 may be equipped with agitators to improve processing efficiency. The top of the pulping tank 3 may be equipped with a water inlet, and an agitator may be installed inside to prevent sedimentation. Figure 1 In the diagram, number 9 is the fresh lime slurry tank, number 10 is the bag filter, and number 11 is the chimney.

[0031] The waste incineration flue gas desulfurization system based on intelligent fly ash sludge reinjection according to the embodiments of the present invention corresponds to... Figure 3 The physical processing module in the system.

[0032] On the other hand, embodiments of the present invention provide a method for desulfurizing flue gas from waste incineration, utilizing the aforementioned waste incineration flue gas desulfurization system based on intelligent fly ash sludge reinjection, such as... Figure 2-3 As shown, it includes: Step S1, Fly Ash Washing and Slurry Preparation: Collect fly ash and send it to pre-dissolving tank 1, add water, stir, and aerate at the bottom. The generated ammonia-containing waste gas is extracted to the waste gas treatment system. The pre-washed slurry is dechlorinated by a solid-liquid separation device, and the desalinated sludge is sent to slurry tank 3 and mixed with water to prepare fly ash slurry. The concentration of fly ash slurry can be flexibly set as needed, such as 5%-15%. In this step, the fly ash contains unreacted NH3 from SNCR denitrification. During the water addition and stirring process, the pH value of the slurry is between 11 and 13 (the high pH is due to the presence of unreacted Ca(OH)2 in the fly ash). Under a strongly alkaline environment, ammonium ions in the aqueous solution will generate NH3. At the same time, aeration increases the gas-liquid contact area, resulting in a lower partial pressure of NH3 in the gas phase, making it easier for NH3 in the liquid phase to escape. Furthermore, aeration can continuously remove NH3 from the water surface, promoting the complete conversion of ammonium to NH3.

[0033] Step S2, Real-time acquisition of multi-source data: Real-time acquisition of flue gas flow rate and acid gas concentration at the SDA tower inlet, acid gas concentration in the net flue gas at the outlet, and the real-time effective alkalinity A of fly ash slurry in slurry tank 3. slurry ; This step corresponds to Figure 3The data monitoring module in the system may specifically include: Flue gas monitoring: A CEMS analyzer is installed at the inlet flue of the SDA tower to measure HCl concentration, SO2 concentration, flue gas flow rate Q and temperature; a CEMS analyzer is installed at the outlet of the SDA tower (after the bag filter 10) to measure the HCl concentration and SO2 concentration of the clean flue gas.

[0034] Slurry monitoring: The slurry preparation tank 3 is equipped with a pH meter and an online alkalinity titrator, which can use photoelectric colorimetry or automatic potentiometric titration to output the real-time effective alkalinity A of the fly ash slurry every preset time interval (which can be flexibly set as needed, such as 5 minutes). slurry ; lime slurry preparation tank (i.e. Figure 1 The fresh lime slurry tank 9) is equipped with a concentration meter to output the real-time effective alkalinity A of the fresh lime slurry. lime .

[0035] Step S3: Dynamic Calculation and Nonlinear Dynamic Allocation of Total Caustic Soda Demand: Based on the inlet flue gas parameters, the feedforward caustic soda demand is calculated using a feedforward model; based on the outlet flue gas parameters, the feedback correction caustic soda demand is calculated using a feedback model; and the weighted fusion yields the total caustic soda demand M at the current moment. total The maximum amount of alkali that the (fly ash) slurry can provide is calculated. The slurry flow rate command is output through nonlinear allocation logic (threshold judgment or flexible saturation function) to ensure that the slurry flow rate approaches the maximum safe flow rate as demand increases. The remaining gap is accurately replenished by fresh lime slurry. Step S4, Execution and Closed Loop: The mud flow command and lime slurry flow command obtained in step S3 are sent to the corresponding regulating valves and variable frequency pumps for execution, and the clean flue gas concentration is continuously monitored to form a closed loop.

[0036] The waste incineration flue gas desulfurization method of this invention corresponds to... Figure 3 The intelligent decision-making module within the system can operate periodically, with the operating cycle flexibly set as needed, for example, every 10-30 seconds. The mud flow command is provided by... Figure 3 The execution structure A in the middle is executed, and the lime slurry flow command is executed by... Figure 3 The execution structure B in the middle is executed. Figure 3 The fresh slaked lime pulping system can be built using existing technology, so it will not be described in detail here.

[0037] In this embodiment of the invention, step S3 involves a "nonlinear dynamic allocation mechanism based on real-time alkalinity sensing", which may specifically include the following two parallel implementation methods.

[0038] Implementation Method 1: Algorithm Based on Threshold Judgment and Adaptive Feedforward Weights In this embodiment, step S3 includes: Step A1: Calculate the total alkali requirement M total Mtotal = α · M feedforward + β · M feedback Where α is the feedforward weighting coefficient (initial value is 0.7), M feedforward M represents the feedforward alkali demand, β is the feedback weighting coefficient (initial value is 0.3), and M... feedback To provide feedback on the alkali demand, α + β = 1, M total M feedforward M feedback The units are all kg / h; In this step, M is preferred. feedforward = k HCl · C HCl · Q + k SO2 · C SO2 · Q + C base , where k HCl k SO2 K is the stoichiometric coefficient (used to calculate the amount of calcium hydroxide required to remove HCl and SO2). HCl The value can range from 0.0011 to 0.0013, k SO2 The value can range from 0.0015 to 0.0018, all of which are dimensionless; C HCl C SO2 These are the real-time concentrations of HCl and SO2 at the inlet, in mg / Nm³. 3 Q represents flue gas flow rate, in Nm³. 3 / h;C base The system's fundamental loss constant has a value ranging from 5 kg / h to 15 kg / h, preferably 8 kg / h; M feedback The incremental PID algorithm is used to calculate: based on the outlet concentration deviation e(t) = C target - C actual The calculation shows that, C target To set target values ​​for emission concentrations (such as 70% of the limit), C actual These are the actual monitored values ​​for emission concentrations. In practice, the outlet concentration deviations of HCl and SO2 can be calculated separately, with the larger deviation being the primary consideration.

[0039] Step A2: Calculate the maximum effective alkali content M that the current fly ash slurry can provide. slurry_available M slurry_available =A slurry Q slurry_max · η, where A slurry Q represents the real-time effective alkalinity of fly ash slurry in the slurry preparation tank, expressed in kg-alkali / m³-slurry. slurry_maxThe maximum safe flow rate allowed for the mud return injection pipeline is expressed in m³ / h (determined by the capacity of the hardware pump). η is the safety factor for mud reactivity (valued at 0.85; however, this is reduced because the reactivity of pure fly ash is lower than that of new lime). M slurry_available The unit is kg / h; Step A3: The intelligent allocation decision logic can be as follows: IF M slurry_available ≥ M total THEN (This indicates there is enough mud) Set the target mud flow rate = M total / A slurry Set the target value for lime slurry flow rate to 0. ELSE IF M slurry_available <M total THEN (This indicates that there is not enough mud and fresh lime is needed to fill the gap). Set the target mud flow rate = Q slurry_max (Maximize the use of mud) Calculate the amount of base required to fill the gap = M total - M slurry_available A lime Real-time effective alkalinity of fresh lime slurry, expressed in kg-alkali / m³-lime slurry; Set the target value for lime slurry flow rate as: Alkali deficit / A lime .

[0040] Furthermore, step A3 may be followed by: Step A4 (Adaptive dynamic adjustment of feedforward weighting coefficient α): When A is detected in the pulping tank... slurry When a sharp drop occurs, temporarily increase the feedforward weighting coefficient α.

[0041] In practice, when monitoring A inside the pulping tank... slurry When a sharp drop occurs (e.g., a drop of more than 20% compared to the previous hour), it indicates a low content of unreacted hydrated lime in the fly ash, resulting in a slower slurry reaction rate. This triggers an adaptive adjustment: the feedforward weighting coefficient α is temporarily increased from 0.7 to 0.85 (more dependent on the large amount of inlet concentration added in advance), while the feedback weighting coefficient β is decreased to 0.15 to overcome the hysteresis effect caused by the slower reaction kinetics of pure fly ash slurry.

[0042] Implementation Method 2: Algorithm Based on Alkalinity Variation Compensation and Flexible Saturation Function In this embodiment, step S3 includes: Step B1 (rate of change feedforward compensation): Calculate the rate of change of mud alkalinity: Calculate the lag compensation amount: (When alkalinity decreases, V) A If the value is negative, the alkali quantity will be automatically increased in advance. Calculate the feedforward alkali demand: , where A slurry，当前 Let A be the current moment. slurry A slurry，上一周期 For A at the previous moment slurry All units are kg / m³ 3 ; V is the time interval between the current moment and the previous moment, in hours (h). A The unit is kg / (m 3 ·h); Q slurry_max T represents the maximum safe flow rate allowed for the mud return injection pipeline, in m³ / h. d M is the residence time of the SDA column reaction, in hours (h). base For routine chemical measurement requirements, the value range changes dynamically with the flue gas volume and pollutant concentration. For the case operation, it is 100-250 kg / h. Step B2 (Nonlinear Feedback): Based on outlet concentration deviation Calculate the required amount of alkali: To suppress overshoot when there is a large deviation, where K is the maximum feedback compensation threshold for a single cycle; In this step, during the desulfurization control, K represents "the maximum absolute value of alkali that the system is allowed to add (or reduce) due to outlet concentration deviation within a single control cycle," in kg / h. When a severe impact of the inlet flue gas causes the outlet concentration to exceed the limit significantly, this prevents the conventional PID algorithm from calculating an extremely exaggerated dosage due to "over-panic," thus avoiding subsequent severe "overshooting" (i.e., excessive dosage leading to an excessively low outlet concentration, wasting expensive lime, and causing a large increase in desulfurization ash and system scaling). A value of 15-40 is recommended, with a typical value of 25.

[0043] Operating Condition 1: Linear Smooth Response under Small Deviation Assume that at a certain moment, the actual concentration C at the outlet is... actual The value is 8 mg / Nm³, and the deviation e(t) = 7 - 8 = -1 mg / Nm³ (the negative sign indicates that alkali needs to be added).

[0044] Substituting into the formula to calculate the nonlinear part: (1 - e^-1) / 1 = 0.632; Feedback on alkali demand: M feedback = 25 × 0.632 × (-1) = -15.8kg / h.

[0045] That is, under small deviations, the function exhibits characteristics similar to conventional proportional control, gently outputting an alkali addition command of 15.8 kg / h.

[0046] Operating Condition 2: Smoothing and Overshoot Prevention under Large Deviation Assuming a sudden increase in the chlorine content of the waste fed into the furnace, the actual concentration at the outlet soars to C. actual The value is 15 mg / Nm³, and the deviation e(t) = 7 - 15 = -8 mg / Nm³.

[0047] Substituting into the formula to calculate the nonlinear part: (1 - e^-8) / 8 ≈ (1 - 0.0003) / 8 ≈ 0.125; Feedback on alkali demand: M feedback = 25 × 0.125 × (-8) = -25kg / h.

[0048] It can be clearly seen that although the deviation increased from 1 to 8 (an increase of 700%), due to the limiting effect of large K, the feedback alkali demand did not surge proportionally to hundreds of kg / h, but was smoothly "clamped" at the safe limit of -25 kg / h. The system does not blindly pour in a massive amount of lime due to a single shock, thus perfectly suppressing the subsequent overshoot risk.

[0049] In this step, the calculation method for the outlet concentration deviation e(t) is the same as before, and will not be repeated here.

[0050] Step B3 (Flexible Saturation Allocation Logic): Calculate the total alkali demand: Calculate the theoretical mud flow rate requirement: Calculate the actual mud flow rate: Where η is the safety factor for mud reactivity and k is the flexible saturation steepness factor; In this step, within the deacidification system, when the theoretical demand fluctuates between "just enough mud" and "insufficient mud requiring lime as a buffer," the value of k determines how quickly the system enters a state of "full-load mud consumption." A larger k value results in a narrower buffer zone, closer to a hard switch; a smaller k value results in a wider buffer zone and a smoother transition. A value of 1.5-3 is recommended, with a typical value of 2, and it is dimensionless.

[0051] Taking a waste incineration plant with a daily processing capacity of 800 tons as an example in the following embodiments, the maximum safe flow rate of the slurry return injection pipeline is set. for Take the flexible saturation steepness coefficient. .

[0052] Assuming a slight increase in inlet HCl at a certain moment, the theoretical mud flow rate is calculated. from Increase to .

[0053] When the demand is 4.0, the actual mud flow rate command = When demand jumps to 5.5, the actual mud flow command = .

[0054] As can be seen, faced with a dramatic demand fluctuation of 37.5%, thanks to the flexible saturation effect of k=2.0, the actual mud flow command only smoothly transitioned from 5.23 to 5.70 (an increase of only 9%), without any abrupt changes. This avoided sudden changes in system pressure caused by an instantaneous full increase in mud flow. Excess alkali demand was smoothly transferred to the lime slurry regulating valve for fine-tuning, completely eliminating the "valve flickering" and mechanical shock during dual-medium co-doping.

[0055] Step B4: Calculate the lime slurry flow rate: , where A lime The real-time effective alkalinity of fresh lime slurry.

[0056] Implementation Cases and Comparative Examples The system was being retrofitted at a waste incineration plant with a daily processing capacity of 800 tons. The inlet HCl concentration fluctuated wildly between 800-1500 mg / Nm³, and the SO2 concentration fluctuated between 150-400 mg / Nm³. The emission requirements were HCl ≤ 10 mg / Nm³ and SO2 ≤ 30 mg / Nm³.

[0057] Comparative Example 1: Using the fixed-ratio backjet technology described in CN115779648B Fly ash is not washed with water to remove ammonia, but is directly mixed and ground with lime to make slurry. The return spray system adopts conventional single-loop PID control (the total slurry volume is adjusted only according to the outlet concentration, and the ratio of fly ash slurry to lime slurry is fixed at 2:8).

[0058] Operational results: Due to the lack of ammonia removal, occasional ammonia escape from the flue gas exceeded the standard (>8ppm); when the inlet HCl suddenly increased to 1500mg / Nm³, the fixed proportion of fly ash slurry could not react in time, resulting in the outlet HCl peak reaching 12mg / Nm³ (exceeding the standard); to prevent exceeding the standard, the operator was forced to manually increase the overall lime concentration, resulting in an average monthly fresh slaked lime consumption of 42kg / ton of waste.

[0059] Comparative Example 2: Pure fly ash water-washed mud re-injection + conventional fixed-parameter PID control (without the intelligent allocation and adaptive control of this invention) The hardware water washing system of the present invention is adopted, but the control system uses a common PID, does not monitor the alkalinity of the mud, and sprays back the mud at a fixed flow rate, adding lime for any insufficient flow.

[0060] Execution results: When the fly ash source changes, causing mud A slurryWhen the slurry concentration suddenly dropped from 15 kg / m³ to 8 kg / m³, the conventional PID system, unaware of the deterioration, continued to add slurry according to the original instructions, resulting in a severe under-spraying of the system. The outlet HCl concentration fluctuated between 9-13 mg / Nm³ for two consecutive hours, triggering an environmental warning.

[0061] Example 1: Using the first technical solution of the present invention (corresponding to the first embodiment described above) Execution result: Environmental indicators: Pre-washing aeration completely solved the ammonia escape problem (outlet ammonia <1ppm). Regardless of inlet fluctuations, outlet HCl remained stable at 4-6mg / Nm³, and SO2 remained stable at 10-18mg / Nm³, with no instantaneous exceedances.

[0062] Example 2: Using the second technical solution of the present invention (corresponding to the aforementioned embodiment 2) The environmental protection indicators are consistent with those of Example 1. The special advantage is that when the inlet HCl fluctuates frequently and slightly between 1000-1100 mg / Nm³ (at the critical point where the mud is just enough and not enough), the lime slurry regulating valve of Example 1 exhibits a "flickering" phenomenon of opening and closing once per minute; while the lime slurry valve opening of Example 2 shows a smooth 0.5%-2% fine adjustment, extending the equipment life and resulting in a smooth CEMS data curve without jagged edges.

[0063] Economic indicators: The intelligent algorithm captures changes in mud alkalinity in real time. When the mud alkalinity reaches 18 kg / m³, the algorithm determines that the mud is sufficient and reduces the flow rate of new lime slurry to 0. When the mud alkalinity drops to 8 kg / m³, the algorithm adaptively increases the feedforward weight and quickly initiates precise bottom-up lime slurry application. The average monthly consumption of fresh hydrated lime is reduced to 26 kg / ton of waste, saving 38% of fresh lime compared to Comparative Example 1.

[0064] The performance comparison is shown in Table 1 below.

[0065] Table 1 As can be seen from the above, compared with CN115779648B, this invention not only stays at the level of "material reuse" but also delves into the level of "intelligent and precise disposal of complex fluctuating materials". CN115779648B uses a fixed ratio mixing, which is essentially an open-loop mechanical operation; while this invention clearly identifies the characteristics of drastic alkalinity fluctuations in pure fly ash slurry due to different sources (fluctuating from 8 to 18 in the examples), and creatively introduces a closed-loop control mechanism of "real-time alkalinity sensing + dynamic fallback allocation". Experimental data (comparison between Example 1 and Comparative Example 2) strongly demonstrates that without the intelligent algorithm of this invention, simple fly ash reuse not only fails to save costs but also causes serious environmental pollution accidents. More importantly, the "flexible saturation allocation algorithm (Implementation Method 2)" proposed in this invention fundamentally solves the actuator jump problem caused by dual-medium switching in traditional threshold control, achieving high-precision and stable control standards at the thermal power plant level while ensuring a 38% cost reduction.

[0066] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A waste incineration flue gas desulfurization system based on intelligent fly ash sludge reinjection, characterized in that, This includes a pre-dissolving tank for ammonia removal, a washing tank for dechlorination, and a pulping tank for pulping, wherein: The pre-dissolving tank is provided with a process water inlet and a fly ash inlet. The fly ash inlet is used to connect to the ash silo. An aeration pipe is provided on the bottom side of the interior of the pre-dissolving tank. A sealed top cover is provided on the top of the pre-dissolving tank. An exhaust port is provided on the sealed top cover. The inlet of the washing tank is connected to the outlet of the pre-dissolving tank, the outlet of the washing tank is connected to the inlet of the solid-liquid separation device, and the filtrate outlet of the solid-liquid separation device is connected to the wastewater tank through a pipeline. The solid discharge port of the solid-liquid separation device is connected to the inlet of the slurry tank, and the outlet of the slurry tank is connected to the desuperheating water inlet of the rotary atomizer at the top of the SDA tower via a mud pump.

2. The waste incineration flue gas desulfurization system based on intelligent fly ash sludge reinjection according to claim 1, characterized in that, The bottom of the ash silo is connected to a pneumatic conveying pipeline via a discharger, and the outlet of the pneumatic conveying pipeline extends into the top of the pre-dissolving tank. And / or, both the pre-dissolving tank and the washing tank are equipped with a stirrer; And / or, the aeration pipe is connected to a Roots blower via a pipeline; And / or, the exhaust outlet is used to connect to the front-end quench tower or pickling exhaust gas treatment system of the plant via an exhaust fan and pipeline.

3. The waste incineration flue gas desulfurization system based on intelligent fly ash sludge reinjection according to claim 1, characterized in that, The pre-dissolving tank is arranged above the washing tank, and the bottom of the pre-dissolving tank is connected to the top of the washing tank through a pipe. The pre-dissolving slurry enters the washing tank by gravity for washing. And / or, the bottom of the washing tank is equipped with a transfer pump, which transports the washing liquid to the inlet of the solid-liquid separation device; And / or, the solid-liquid separation device is a hydrocyclone and a plate and frame filter press connected in sequence, or a horizontal centrifuge; And / or, the wastewater outlet of the wastewater tank is connected via a transfer pump to the pre-dissolving tank and the washing tank, and via another connection to the evaporation and salt separation system.

4. The waste incineration flue gas desulfurization system based on intelligent fly ash sludge reinjection according to claim 1, characterized in that, The top of the pulping tank is equipped with a water inlet, and the inside is equipped with a stirrer; And / or, the outlet pipeline of the mud pump is equipped with an electromagnetic flow meter and an electric regulating valve.

5. A method for desulfurizing flue gas from waste incineration, utilizing the waste incineration flue gas desulfurization system based on intelligent fly ash slurry reinjection as described in any one of claims 1-4, characterized in that, include: Step S1, Fly ash washing and pulping: Collect fly ash and send it into a pre-dissolving tank, add water and stir and aerate at the bottom. The generated ammonia-containing waste gas is pumped to the waste gas treatment system. The pre-washed slurry is dechlorinated by a solid-liquid separation device, and the desalted sludge is sent into a pulping tank and water is added to prepare fly ash slurry. Step S2, Real-time Acquisition of Multi-Source Data: Real-time acquisition of flue gas flow rate and acid gas concentration at the SDA tower inlet, acid gas concentration in the net flue gas at the outlet, and the real-time effective alkalinity A of fly ash slurry in the slurry mixing tank. slurry ; Step S3: Dynamic Calculation and Nonlinear Dynamic Allocation of Total Caustic Soda Demand: Based on the inlet flue gas parameters, the feedforward caustic soda demand is calculated using a feedforward model; based on the outlet flue gas parameters, the feedback correction caustic soda demand is calculated using a feedback model; and the weighted fusion yields the total caustic soda demand M at the current moment. total The maximum amount of alkali that the mud can provide is calculated, and the mud flow rate command is output through nonlinear distribution logic to ensure that the mud flow rate approaches the maximum safe flow rate as demand increases, and the remaining gap is accurately replenished by fresh lime slurry. Step S4, Execution and Closed Loop: The mud flow command and lime slurry flow command obtained in step S3 are sent to the corresponding regulating valves and variable frequency pumps for execution, and the clean flue gas concentration is continuously monitored to form a closed loop.

6. The method according to claim 5, characterized in that, The SDA tower inlet flue is equipped with a CEMS analyzer to measure HCl, SO2, flue gas flow rate Q, and temperature; And / or, a CEMS analyzer is installed after the bag filter at the SDA tower outlet to measure HCl and SO2 in the clean flue gas; And / or, the pulping tank is equipped with a pH meter and an online alkalinity titrator, which uses photoelectric colorimetry or automatic potentiometric titration to output the real-time effective alkalinity A of the pulp at preset time intervals. slurry ; And / or, the lime slurry preparation tank is equipped with a concentration meter to output the real-time effective alkalinity A of the fresh lime slurry. lime .

7. The method according to claim 5, characterized in that, Step S3 includes: Step A1: Calculate the total alkali requirement M total M total = α · M feedforward + β · M feedback Where α is the feedforward weighting coefficient, and M feedforward M represents the feedforward alkali demand, β is the feedback weighting coefficient, and M... feedback To provide feedback on the alkali demand, α + β = 1; Step A2: Calculate the maximum effective alkali content M that the current mud can provide. slurry_available M slurry_available = A slurry ·Q slurry_max · η, where A slurry Q represents the real-time effective alkalinity of fly ash slurry in the pulping tank. slurry_max η is the maximum safe flow rate allowed for the mud return injection pipeline, and η is the safety factor for mud reactivity. Step A3: Perform intelligent allocation, if M slurry_available ≥ M total Then set the target value of mud flow rate = M total / A slurry Set the target value for lime slurry flow rate to 0; otherwise, set the target value for mud slurry flow rate to Q. slurry_max Calculate the amount of alkali required to fill the gap = M total - M slurry_available Set the target value for lime slurry flow rate as: Target value = Alkali deficit / A lime , where A lime The real-time effective alkalinity of fresh lime slurry.

8. The method according to claim 7, characterized in that, In step A1, M feedforward = k HCl · C HCl · Q+ k SO2 · C SO2 · Q + C base , where k HCl k SO2 C is the stoichiometric coefficient. HCl C SO2 These represent the real-time concentrations of HCl and SO2 at the inlet, respectively; Q is the flue gas flow rate; and C... base This is the system's fundamental loss constant; M feedback The incremental PID algorithm is used to calculate: based on the outlet concentration deviation e(t) = C target - C actual The calculation shows that, C target To set target values ​​for emission concentrations, C actual These are the actual monitored values ​​for emission concentrations.

9. The method according to claim 7, characterized in that, Following step A3, the following is also included: Step A4: When monitoring A in the pulping tank slurry When a sharp drop occurs, temporarily increase the feedforward weighting coefficient α.

10. The method according to claim 5, characterized in that, Step S3 includes: Step B1: Calculate the rate of change in mud alkalinity: Calculate the lag compensation amount: Calculate the feedforward alkali demand: , where A slurry，当前 Let A be the current moment. slurry A slurry，上一周期 For A at the previous moment slurry , Q represents the time interval between the current moment and the previous moment. slurry_max T is the maximum safe flow rate allowed for the mud return pipeline. d M represents the residence time of the SDA column reaction. base For routine chemical metrology requirements; Step B2: Based on the outlet concentration deviation Calculate the required amount of alkali: Where K is the maximum feedback compensation threshold for a single cycle; Step B3: Calculate the total alkali requirement: Calculate the theoretical mud flow rate requirement: Calculate the actual mud flow rate: Where η is the safety factor for mud reactivity and k is the flexible saturation steepness factor; Step B4: Calculate the lime slurry flow rate: , where A lime The real-time effective alkalinity of fresh lime slurry.

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