A desulfurization energy consumption optimization control system

Abstract

The application discloses a desulfurization energy consumption optimization control system, and belongs to the technical field of flue gas wet desulfurization, and comprises a desulfurization slurry component on-line measurement system, an oxidation air energy-saving closed-loop control system, a slurry circulating pump on-line combination optimization system and a SO2 / pH dual-target intelligent slurry supply system. The desulfurization energy consumption optimization control system can realize dynamic measurement of the concentration of sub-sulfate ions in a desulfurization tower, obtain an oxidation air blower operation strategy through deep learning, accurately predict the disturbance caused by unit load, coal quality, combustion and other signals by establishing a wet desulfurization mathematical model, and then realize accurate and stable control of the slurry pH value and the outlet SO2 concentration, so that the waste of desulfurizing agent is reduced, the slurry circulating pump power consumption is reduced, the operation cost of the desulfurization system is reduced to the greatest extent, and a comprehensive solution is provided for safe, stable and energy-saving operation of the desulfurization system in the power industry.

Description

Technical Field

[0001] This invention belongs to the field of wet flue gas desulfurization technology, specifically relating to a desulfurization energy consumption optimization and control system. Background Technology

[0002] Wet flue gas desulfurization (FGD) systems are massive energy and material consumption systems, including flue gas systems, slurry preparation systems, absorption systems, gypsum dewatering systems, wastewater treatment systems, thermal control systems, and electrical systems. Each subsystem contains high-energy-consuming equipment such as pumps and fans. The power consumption of the desulfurization system accounts for 1 / 3 of the plant's total power consumption. The equipment is designed according to the boiler's BMCR flue gas volume and the highest sulfur content of coal fed into the boiler in recent years. As the load decreases and the coal quality changes, the desulfurization system still operates according to the design conditions, resulting in a huge waste of energy and materials.

[0003] Furthermore, the pH control of the desulfurization tower slurry is significantly affected by flue gas volume and inlet SO2 levels. Parameters change drastically with large load fluctuations, and slurry pH measurement exhibits a significant lag. Traditional PID automatic adjustment control strategies are not very effective. Often, operators rely on their experience to manually adjust the slurry pump frequency or slurry valve opening for coarse pH control, failing to precisely regulate the desulfurization tower slurry quality, resulting in decreased desulfurization efficiency and wasted desulfurizing agent. Simultaneously, to ensure hourly average values ​​do not exceed limits, operators often increase the liquid-to-gas ratio, meaning the slurry circulation pump is not optimized for operation, potentially leading to excessive output and unnecessary power consumption. Summary of the Invention

[0004] This invention provides a desulfurization energy consumption optimization and control system. Based on the dynamic measurement of sulfite ion concentration in the desulfurization tower, the system obtains the operation strategy of the oxidation blower through deep learning. By establishing a mathematical model of wet desulfurization, it accurately predicts the disturbances caused by signals such as unit load, coal quality, and combustion, thereby achieving precise and stable control of slurry pH and outlet SO2 concentration. This reduces desulfurizing agent waste, lowers slurry circulation pump power consumption, and minimizes the operating cost of the desulfurization system, providing a comprehensive solution for the safe, stable, and energy-saving operation of desulfurization systems in the power industry.

[0005] To achieve the above-mentioned technical objectives, the present invention is implemented through the following technical solution:

[0006] A desulfurization energy consumption optimization control system, comprising:

[0007] An online measurement system for desulfurization slurry composition is used to monitor sulfite, pH, and ORP in the slurry in real time. The online measurement system for desulfurization slurry composition includes: a comprehensive sampling platform and an elemental measurement system. The comprehensive sampling platform is used to sample the slurry during system operation and automatically recirculates the slurry after measurement. The elemental measurement system is equipped with a sulfite meter, a pH meter, and an ORP meter.

[0008] The oxidation air energy-saving closed-loop control system adopts the sulfite and oxidation rate indicators obtained by the online measurement system of desulfurization slurry components in real time, combined with the real-time load and coal quality conditions. Based on the oxidation air volume optimization model prediction in the DCS system, as well as the physical models of material consumption, energy consumption and emissions, the system obtains the oxidation fan operation strategy and performs the control and adjustment of oxidation fan current and the switching of the number of oxidation fans.

[0009] The online combination optimization system for slurry circulation pumps derives an optimized combination operation strategy for slurry circulation pumps based on the unit's real-time load, SO2 inlet and outlet concentrations, and over-limit conditions, using a slurry circulation pump combination optimization model.

[0010] The SO2 / pH dual-objective intelligent slurry supply system intelligently optimizes the SO2 content of the flue gas and uses the upper and lower limits of the pH value as constraints. By introducing online parameters such as unit load, flue gas volume, inlet and outlet SO2, and slurry supply volume, the system uses a dynamic prediction model to respond to changes in inlet SO2 and load, thereby controlling the pH value to stabilize and achieving closed-loop control of SO2 in the flue gas.

[0011] Preferably, the integrated sampling platform includes:

[0012] The slurry sample return pipe has its inlet and outlet ends connected to the desulfurization tower and located below the surface of the desulfurization slurry. The inlet side of the slurry sample return pipe is a horizontal pipe section, and the outlet side is an inclined pipe section that slopes downwards. The horizontal pipe section and the inclined pipe section are connected by a vertical pipe section integrally formed.

[0013] A slurry pump is installed on the horizontal pipe section;

[0014] The element measurement system includes: a sulfite measuring instrument and its probe, a pH measuring instrument and its probe, and an ORP measuring instrument and its probe.

[0015] The vertical pipe section is equipped with three sets of probe connectors at equal intervals; the three sets of probe connectors are arranged from top to bottom as follows: sulfite measuring instrument probe, pH measuring instrument probe, and ORP measuring instrument probe.

[0016] Preferably, the method for building the oxidation air volume optimization model is as follows:

[0017] S1: Calculation of theoretical oxygen demand based on chemical reaction mechanism

[0018] In desulfurization systems, sulfite (SO3) 2- ) is oxidized to sulfate (SO4) 2- The core reaction is: 1 mol SO3 2- 0.5 mol O2 is required; the oxygen demand must take into account both the current unoxidized sulfite reserves and the increase in newly generated sulfite.

[0019] Existing oxidation demand:

[0020] Total amount of unoxidized sulfite in slurry:

[0021]

[0022] Corresponding O2 demand:

[0023]

[0024] ( =80g / mol =32g / mol)

[0025] Incremental oxidation demand:

[0026] SO2 in the flue gas is first converted into sulfite after entering the slurry, and the newly generated SO3 2- The rate is consistent with the SO2 removal rate:

[0027]

[0028] Newly generated SO3 2- Corresponding O2 demand:

[0029] ， =64g / mol

[0030] Total oxygen demand:

[0031] , (1- ƞ / 100 represents the proportion of unoxidized stock).

[0032] S2: Converts oxygen demand into air volume.

[0033] The volumetric O2 content in the air is 21%, the oxygen utilization rate of the fan is α (the value of α is determined based on the actual oxygen utilization rate of the fan in use), and the required air volumetric flow rate is:

[0034] (m) 3 / h), =1.429kg / m3

[0035] S3: Correction based on oxidation rate feedback (avoiding over-oxidation or under-oxidation).

[0036] Based on the current oxidation rate Dynamically adjust the theoretical air volume to ensure that the oxidation rate remains stable within the target range;

[0037] like (Insufficient oxidation): Increase airflow and adjust the coefficient. (k is an adjustment factor, usually 0.1-0.3)

[0038] like (Insufficient oxidation): Reduce airflow, adjust coefficient. ;

[0039] Ultimate optimal airflow:

[0040] .

[0041] The meanings of the above parameters are as follows:

[0042] Input parameters:

[0043] Slurry parameters: Sulfite concentration (mg / m 3 Current oxidation rate (%) slurry volume V (m) 3 ), slurry temperature T (°C);

[0044] Flue gas parameters: Unit load P (MW, reflecting flue gas volume), coal sulfur content S (%, reflecting SO2 concentration), flue gas volume Q 烟气 (m) 3 / h), SO2 exports Inlet SO2 concentration (mg / m 3 );

[0045] Equipment parameters: Blower oxygen utilization rate α (%, i.e., the proportion of O2 actually participating in the reaction to the total blown O2, which is related to stirring intensity and slurry mixing degree).

[0046] Preferably, the physical model for material consumption is for the consumption of desulfurizing agent, and the desulfurizing agent is limestone (CaCO3);

[0047] The limestone consumption model and its construction method are as follows:

[0048] In the desulfurization reaction, CaCO3 needs to neutralize the acidity generated by SO2:

[0049]

[0050] If oxidation is insufficient, that is Too low, SO3 2- Accumulation will lower the pH value of the slurry and inhibit the dissolution of CaCO3, requiring excessive addition of CaCO3 to maintain pH stability.

[0051]

[0052] This refers to the amount of SO2 removed.

[0053] =100g / mol =64g / mol, stoichiometric ratio is 100 / 64≈1.56;

[0054] k3 is the oxidation deficiency correction factor (measured). If material consumption increases by 20%, then k3 = 0.2).

[0055] Gypsum moisture content model

[0056] Oxidation rate When the concentration is too high (>95%), calcium sulfate (CaSO4·2H2O) crystals become too fine, making dehydration difficult and increasing the water content; oxidation rate... When the moisture content is less than 80%, the mixing of calcium sulfite (CaSO3·0.5H2O) with gypsum also leads to an increase in moisture content; optimal parameters The gypsum particles are uniform and have the lowest moisture content.

[0057] Moisture content of gypsum

[0058] Fitting parameters: a and b are model fitting coefficients, obtained from experimental data (different oxidation rates). The following gypsum dehydration test) determines a and b, when When W is at its minimum, which is 10%, then b = 10; When W=15%, then a=5 / 15 2 =0.022.

[0059] Limestone consumption The gypsum moisture content W is maintained at the optimal value for oxidation air volume, and the number of oxidation fans and their power are automatically switched on and off based on the optimal oxidation air volume.

[0060] Preferably, the energy consumption physical model and its construction method are as follows:

[0061] The energy consumption of an oxidation blower is directly related to its air volume and air pressure, and its power formula is based on fluid mechanics principles:

[0062]

[0063] In the above formula, each parameter is defined as:

[0064] Q 实际 Actual output air volume of a single fan, in meters. 3 / h, derived from the oxidation airflow optimization model Q air,opt Allocation

[0065] p 风压 The blower outlet air pressure, in Pa, is related to the slurry level and pipeline resistance, and can be monitored in real time by a pressure sensor.

[0066] Fan efficiency, a non-linear parameter that varies with air volume, is fitted using a performance curve provided by the manufacturer.

[0067] Motor efficiency is between 90% and 95%, with the highest efficiency occurring near the rated load.

[0068] 3600: Unit conversion factor, one hour is 3600 seconds.

[0069] Preferred energy consumption correction model for switching multiple oxidation blowers:

[0070] When the total air volume demand exceeds the maximum airflow of a single fan, multiple fans need to be put into operation. In this case, the following needs to be considered:

[0071] Unit allocation: Total optimal airflow Q air,opt Distribute the load among the operating fans to avoid overloading any single unit.

[0072] Start-up and shutdown energy consumption: There is an inrush current when the fan starts (approximately 5-7 times the rated current). The energy consumption for a single start-up can be calculated as 1.5 times the rated power for 10 seconds (i.e., ΔP = 1.5 × P). 额定 (×10 / 3600), during operation, frequent switching should be avoided;

[0073] Total energy consumption formula:

[0074] P

[0075] In the above formula, each parameter is defined as: n： Number of operating fans; N 切投 Number of times the ball is switched and thrown per unit of time; k 4 Start-stop energy consumption coefficient, set to 1.2 to cover additional losses.

[0076] Preferably, the emission physical model and its construction method are as follows:

[0077] The core of the emission model is to ensure that the SO2 concentration in the flue gas after desulfurization meets the standards.

[0078] Relationship between desulfurization efficiency and oxidation rate

[0079] Desulfurization efficiency (The proportion of SO2 removed from the inlet is affected by the oxidation rate) (Impact)

[0080] Oxidation rate too low ( SO3 in slurry 2- Accumulation, inhibiting SO2 dissolution ( The balance shifts to the left, leading to a decrease in desulfurization efficiency;

[0081] The oxidation rate is too high ( ): Slurry SO4 2- High concentrations may be related to... Ca 2+ A supersaturated solution is formed, crystals cover the surface of limestone, and its activity is reduced;

[0082] Related formula:

[0083]

[0084] In the above formula, each parameter is defined as:

[0085] coefficient c 1 -c 4 : c 1 By fitting historical oxidation rate data c 2 Fitting historical pH data of the slurry c 3 By fitting historical data of slurry flow rate c 4 The desulfurization efficiency was fitted using historical data; among which... c 1 For positive, c 2 It is positive;

[0086] Based on desulfurization efficiency The SO2 outlet concentration is:

[0087] (mg / m 3 )

[0088] ≤35mg / m 3If the model prediction exceeds the limit, the oxidation air volume must be forcibly increased.

[0089] Preferably, the method for building the slurry circulation pump combination optimization model is as follows:

[0090] Minimum necessary spray volume calculation

[0091] The relationship between spray volume and desulfurization efficiency follows the law of diminishing marginal returns; after the spray volume increases to a certain extent, the improvement in desulfurization efficiency slows down. The relationship between the two is fitted based on historical data.

[0092]

[0093] k 5 ,k 6 ,k 7 : Fit coefficient ( k 5 >0, increased spray volume promotes desulfurization; k 6 >0, increased pH enhances absorption; k 7 (Based on historical desulfurization efficiency fitting)

[0094] The SO2 concentration at the export site must meet the standard, i.e.

[0095] (Inlet SO2 concentration > 35 mg / m³) 3 hour)

[0096] The minimum spray volume is obtained based on the target desulfurization efficiency:

[0097]

[0098] When the flue gas volume increases, the spray volume needs to be increased proportionally to ensure a stable gas-liquid ratio (spray volume / flue gas volume). Correction coefficient. Therefore:

[0099]

[0100] Pump combination flow rate and energy consumption calculation:

[0101] Assume the pump combination is as follows

[0102] (m≤N), then:

[0103] Total spray volume:

[0104] , Actual flow rate of a single pump

[0105] Total energy consumption:

[0106] ,in P i (Q i ) Calculations were made based on the pump power curve and fitted with data from the manufacturer.

[0107] Sprinkler coverage constraints:

[0108]

[0109] When multiple pumps are running, the total coverage rate should avoid overlap and waste and have no blind spots. The total coverage rate is 1, minus the product of the areas not covered by each pump, to ensure that more than 95% of the flue gas cross section is covered by spraying.

[0110] Optimal pump combination selection:

[0111] In satisfying Q 总 ≥Q` 喷淋最小 , f 总 Under the premise of ≥95%, select total energy consumption. P 循环,总 Minimal combination:

[0112]

[0113] The above involves parameter definitions:

[0114] Flue gas parameters: Real-time flue gas volume Q 烟气 （ m 3 / h, positively correlated with unit load)

[0115] Inlet SO2 concentration (mg / m 3 )

[0116] flue gas temperature T 烟气 (℃ affects SO2 dissolution)

[0117] Slurry parameters: Slurry pH value (pH=5.5-6.0, SO2 absorption efficiency is optimal)

[0118] Slurry density: ρ 浆液 (kg / m 3 )

[0119] Equipment parameters:

[0120] Total number of circulating pumps N

[0121] Rated flow rate of a single pump Q泵,额定 (m) 3 / h)

[0122] Single pump power curve P i (Q i ) (kW, flow rate) Q The actual power output is related to the head and efficiency.

[0123] Corresponding spray layer coverage f i (%, the percentage of flue gas cross-section covered when a single pump starts).

[0124] Preferably, in the SO2 / pH dual-objective intelligent slurry supply system, the dynamic prediction model for the slurry supply volume is as follows:

[0125] SO2 Total Input Prediction

[0126] Total amount of SO2 entering the absorption tower per unit time

[0127]

[0128] Target pH calculation

[0129] Based on total SO2 input Based on the current absorption efficiency, the target pH value is obtained.

[0130]

[0131] k 8 ,k 9 ,k 10 The fitting coefficients are obtained from historical data. k 8 A value greater than 0 indicates that a higher pH level is required to increase the total amount of SO2. k 9 A value greater than 0 indicates an increase in circulation volume; therefore, the pH value should be appropriately lowered.

[0132] Q 循环 The slurry circulation spray volume of the circulating pump is the larger the circulation spray volume, the more sufficient the gas-liquid contact, and the lower the pH dependence.

[0133] Grout supply prediction

[0134] To maintain pH stability pH 目标 The slurry supply needs to be adjusted.

[0135]

[0136] ΔpH 历史 The correlation value between changes in slurry supply and pH in historical data.

[0137] k 11 The correction factor, taking into account slurry concentration and limestone activity, is taken as 1.1~1.3;

[0138] The above involves parameter definitions.

[0139] flue gas volume Q 烟气 Inlet SO2 concentration .

[0140] Preferably, the pH upper and lower limit constraint range is set to 5~6.

[0141] The beneficial effects of this invention are:

[0142] 1) Real-time monitoring of sulfite concentration changes, with the oxidation air volume optimization model as the core, and material consumption, energy consumption, and emission models as collaborative constraints, together constitute a multi-objective optimization system to achieve on-demand adjustment of oxidation air volume and reduce oxidation fan power consumption; through this collaboration, the system can achieve energy saving, ensure desulfurization effect, gypsum by-product quality and environmental compliance, forming a complete closed-loop control logic.

[0143] 2) Optimize the operation combination of the slurry circulation pump system to save extra power consumption of the circulation pump; in coordination with the oxidation air volume, if the oxidation rate is insufficient and the desulfurization efficiency decreases, the spray volume can be appropriately increased through pump combination optimization to compensate; conversely, if the oxidation is sufficient, the spray volume can be appropriately reduced to save energy.

[0144] 3) Under the dual constraints of SO2 and pH, the system operates at a controlled level, with automatic and on-demand slurry supply, saving limestone materials; feedforward control is used to proactively address load and inlet SO2 fluctuations, keeping outlet SO2 concentration fluctuations within a low range; pH is maintained stable within the target pH range, avoiding limestone waste caused by maintaining a large slurry supply due to excessively high pH (this can reduce the slurry supply by 5%-10%), while also reducing the risk of insufficient absorption and excessive emissions due to insufficient slurry supply caused by excessively low pH; source parameters such as unit load and flue gas volume are deeply correlated with control parameters such as slurry supply and pH, realizing a shift from passive compliance to proactive optimization. Attached Figure Description

[0145] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0146] Figure 1 This is a schematic diagram of the desulfurization reaction principle of the present invention;

[0147] Figure 2 This is a block diagram illustrating the synergistic working principle of the online measurement system for desulfurization slurry composition, the energy-saving closed-loop control system for oxidation air, the online combination optimization system for slurry circulation pump, and the SO2 / pH dual-target intelligent slurry supply system of the present invention.

[0148] Figure 3 This is a schematic diagram of the online measurement system for desulfurization slurry composition of the present invention;

[0149] In the attached diagram, the structural names represented by each number are as follows:

[0150] 1-Desulfurization tower, 2-Slurry pump, 3-Slurry sample reflux pipe, 4-Sulfite meter, 5-pH meter, 6-ORP meter, 7-Probe connector. Detailed Implementation

[0151] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0152] A desulfurization energy consumption optimization control system, comprising:

[0153] The online measurement system for desulfurization slurry composition is used to monitor sulfite, pH, and ORP in the slurry in real time. The online measurement system for desulfurization slurry composition includes: a comprehensive sampling platform and an element measurement system. The comprehensive sampling platform is used to sample the slurry during system operation and automatically recirculates the slurry after measurement. The element measurement system is equipped with a sulfite meter, a pH meter, and an ORP meter.

[0154] For example, such as Figure 3 As shown, the integrated sampling platform in this embodiment includes:

[0155] The slurry sample return pipe 3 has its inlet and outlet ends connected to the desulfurization tower 1 and located below the liquid surface of the desulfurization slurry. The inlet side of the slurry sample return pipe 3 is a horizontal pipe section, and the outlet side is an inclined pipe section that slopes downward. The horizontal pipe section and the inclined pipe section are connected by a vertical pipe section that is integrally formed.

[0156] A slurry pump 2 is installed on the horizontal pipe section to pump the slurry out of the desulfurization tower 1;

[0157] The element measurement system includes: sulfite meter 4 and its probe, pH meter 5 and its probe, and ORP meter 6 and its probe;

[0158] Three sets of probe connectors 7 are set at equal intervals in the vertical pipe section; the three sets of probe connectors 7 are arranged from top to bottom as follows: sulfite measuring instrument probe, pH measuring instrument probe and ORP measuring instrument probe;

[0159] After the slurry in the desulfurization tower 1 is pumped out, it first reaches the horizontal pipe section on the inlet side of the slurry sample return pipe 3, and then flows into the vertical pipe section. In the vertical pipe section, the slurry comes into contact with the sulfite measuring instrument probe, pH measuring instrument probe and ORP measuring instrument probe in sequence, and the sulfite concentration, pH value and oxidation rate value in the slurry are measured in sequence. The measured values ​​are used as the control reference for the following system.

[0160] The oxidation air energy-saving closed-loop control system adopts the sulfite and oxidation rate indicators obtained by the online measurement system of desulfurization slurry components in real time. It can also combine the real-time load and coal quality conditions, and obtain the oxidation fan operation strategy based on the oxidation air volume optimization model in the DCS system, as well as the physical models of material consumption, energy consumption and emissions, to control and adjust the oxidation fan current and switch the number of oxidation fans.

[0161] An exemplary method for building an oxidation airflow optimization model is as follows:

[0162] S1: Calculation of theoretical oxygen demand based on chemical reaction mechanism

[0163] In desulfurization systems, sulfite (SO3) 2- ) is oxidized to sulfate (SO4) 2- The core reaction is: 1 mol SO3 2- 0.5 mol O2 is required; the oxygen demand must take into account both the current unoxidized sulfite reserves and the increase in newly generated sulfite.

[0164] Existing oxidation demand:

[0165] Total amount of unoxidized sulfite in slurry:

[0166]

[0167] Corresponding O2 demand:

[0168]

[0169] ( =80g / mol =32g / mol)

[0170] Incremental oxidation demand:

[0171] SO2 in the flue gas is first converted into sulfite after entering the slurry, and the newly generated SO3 2- The rate is consistent with the SO2 removal rate:

[0172]

[0173] Newly generated SO3 2- Corresponding O2 demand:

[0174] ， =64g / mol

[0175] Total oxygen demand:

[0176] , ( (This indicates the proportion of unoxidized material in the stock).

[0177] S2: Converts oxygen demand into air volume.

[0178] The volume percentage of O2 in the air is 21%, and the oxygen utilization rate of the fan is α. In this embodiment, the ratio of the actual O2 participating in the reaction to the O2 blown in by the fan is 40%, and this value range is usually 30%-60%.

[0179] Required air volume flow rate:

[0180] (m) 3 / h), =1.429kg / m 3

[0181] S3: Correction based on oxidation rate feedback (avoiding over-oxidation or under-oxidation).

[0182] Based on the current oxidation rate Dynamically adjust the theoretical air volume to ensure that the oxidation rate remains stable within the target range;

[0183] like (Insufficient oxidation): Increase airflow and adjust the coefficient. (k is an adjustment factor, set to 0.2)

[0184] like (Insufficient oxidation): Reduce airflow, adjust coefficient. ;

[0185] Ultimate optimal airflow:

[0186] .

[0187] The meanings of the above parameters are as follows:

[0188] Input parameters:

[0189] Slurry parameters: Sulfite concentration (mg / m 3 Current oxidation rate (%) slurry volume V (m) 3 ), slurry temperature T (°C);

[0190] Flue gas parameters: Unit load P (MW, reflecting flue gas volume), coal sulfur content S (%, reflecting SO2 concentration), flue gas volume Q 烟气 (m) 3 / h), inlet SO2 concentration (mg / m 3 );

[0191] Equipment parameters: Blower oxygen utilization rate α (%, i.e., the proportion of O2 actually participating in the reaction to the total blown O2, which is related to stirring intensity and slurry mixing degree)

[0192] Slurry parameters ( oxidation rate The flue gas parameters ( ) were measured every 1-5 minutes using a sulfite meter and an ORP meter. Q 烟气 , The flue gas online monitoring instrument acquires data once per minute; according to the above model, it acquires data once every 10 seconds. Q air,opt ;

[0193] If a single fan can provide the optimal air volume, the air volume shall not be less than the minimum stable air volume of the single fan; if multiple fans are required to achieve the optimal air volume, the air volume shall not exceed the total rated air volume of the multiple fans.

[0194] The physical model for material consumption is designed for the consumption of desulfurizing agent, specifically limestone (CaCO3). The consumption model for limestone and its construction method are as follows:

[0195] In the desulfurization reaction, CaCO3 needs to neutralize the acidity generated by SO2:

[0196] The generated CaSO3 is oxidized to form CaSO4, which is a byproduct of gypsum.

[0197] If oxidation is insufficient, that is Too low, SO3 2- Accumulation will lower the pH value of the slurry and inhibit the dissolution of CaCO3, requiring excessive addition of CaCO3 to maintain pH stability.

[0198]

[0199] This refers to the amount of SO2 removed.

[0200] =100g / mol =64g / mol, stoichiometric ratio is 100 / 64≈1.56;

[0201] k3 is the oxidation deficiency correction factor (measured). If material consumption increases by 20%, then k3 = 0.2).

[0202] Gypsum moisture content model

[0203] Oxidation rate When the concentration is too high (>95%), calcium sulfate (CaSO4·2H2O) crystals become too fine, making dehydration difficult and increasing the water content; oxidation rate... When the content is less than 80%, calcium sulfite (CaSO3·0.5H2O) mixes into the gypsum, making dehydration difficult and also leading to an increase in moisture content. Experiments have verified that the optimal parameters... The gypsum particles are uniform and have the lowest moisture content;

[0204] Moisture content of gypsum

[0205] Fitting parameters: a and b are model fitting coefficients, obtained from experimental data (different...). The following gypsum dehydration test) determines a and b, when When W is at its minimum, which is 10%, then b = 10; When W=15%, then a=5 / 15 2 =0.022.

[0206] Output of the oxidation air volume optimization model Q air,opt Directly affects oxidation rate ， and It is also fed back as input to the air volume model and drives the material consumption model to calculate limestone consumption and gypsum moisture content, forming a closed-loop synergy of "air volume-oxidation rate-material consumption";

[0207] Based on limestone consumption The system achieves multi-objective optimization by balancing the moisture content of gypsum and the oxidation air volume, keeping the air volume at its optimal value. Based on the optimal oxidation air volume, the DCS system automatically switches the number of oxidation fans and adjusts the power automatically, ensuring that material consumption and by-product quality are controlled within a reasonable range while minimizing the air volume, thus achieving the goal of energy saving for the fans.

[0208] The energy consumption physical model and its construction method are as follows:

[0209] The energy consumption of an oxidation blower is directly related to its air volume and air pressure, and its power formula is based on fluid mechanics principles:

[0210] (kW)

[0211] In the above formula, each parameter is defined as:

[0212] Q 实际 Actual output air volume of a single fan, in meters. 3 / h, derived from the oxidation airflow optimization model Q air,opt Allocation

[0213] p 风压 The blower outlet air pressure, in Pa, is related to the slurry level and pipeline resistance, and can be monitored in real time by a pressure sensor.

[0214] Fan efficiency, a non-linear parameter that varies with air volume, is fitted using a performance curve provided by the manufacturer.

[0215] Motor efficiency is between 90% and 95%, with the highest efficiency occurring near the rated load.

[0216] 3600: Unit conversion factor, one hour is 3600 seconds.

[0217] Obtain the energy consumption of a single wind turbine P 单台 Oxidation fan switching energy consumption correction model:

[0218] When the total air volume demand exceeds the maximum airflow of a single fan, multiple fans need to be put into operation. In this case, the following needs to be considered:

[0219] Unit allocation: Total optimal airflow Q air,opt Distribute the load among the operating fans to avoid overloading any single unit.

[0220] Start-up and shutdown energy consumption: There is an inrush current when the fan starts (approximately 5-7 times the rated current). The energy consumption for a single start-up can be calculated as 1.5 times the rated power for 10 seconds (i.e., ΔP = 1.5 × P). 额定 (×10 / 3600), during operation, frequent switching should be avoided;

[0221] Total energy consumption formula:

[0222] P

[0223] In the above formula, each parameter is defined as: n： Number of operating fans; N切投 Number of times the ball is switched and thrown per unit of time; k 4 Start-stop energy consumption coefficient, set to 1.2 to cover additional losses;

[0224] To meet the optimal air volume Q air,opt Under the premise of ensuring energy efficiency, priority should be given to single-unit speed regulation rather than multiple units operating at low load, so as to achieve the goal of optimizing energy consumption of the fan.

[0225] The emission physical model and its construction method are as follows:

[0226] The core of the emission model is to ensure that the SO2 concentration in the flue gas after desulfurization meets the standard. This embodiment follows the standard of ≤35mg / m³ for key areas. 3 ;

[0227] Relationship between desulfurization efficiency and oxidation rate

[0228] Desulfurization efficiency (The proportion of SO2 removed from the inlet is affected by the oxidation rate) (Impact)

[0229] Oxidation rate too low ( SO3 in slurry 2- Accumulation, inhibiting SO2 dissolution ( The balance shifts to the left, leading to a decrease in desulfurization efficiency;

[0230] The oxidation rate is too high ( SO4 in slurry 2- Too high a concentration may be related to Ca 2+ A supersaturated solution is formed, crystals cover the surface of limestone, and its activity is reduced;

[0231] Related formula:

[0232]

[0233] In the above formula, each parameter is defined as:

[0234] coefficient c 1 -c 4 : c 1 By fitting historical oxidation rate data c 2 Fitting historical pH data of the slurry c 3 By fitting historical data of slurry flow rate c 4 The desulfurization efficiency was fitted using historical data; among which... c 1For positive, c 2 It is positive;

[0235] Based on desulfurization efficiency The SO2 outlet concentration is:

[0236] (mg / m 3 )

[0237] For compliance, if the model predicts that the volume of oxidation air will be increased, it is mandatory to increase the volume of oxidation air.

[0238] The oxidation airflow optimization model is the core, with material consumption, energy consumption, and emission models serving as constraints, together forming a "multi-objective optimization system"; the optimal airflow... Q air,opt Changes in the oxidation rate drive limestone consumption, gypsum moisture content, and SO2 outlet concentration. Q air,opt The system, along with total energy consumption, material consumption, and emission indicators, participates in decision-making. Through this synergy, the system can achieve energy conservation while ensuring desulfurization effectiveness, by-product quality, and environmental compliance, forming a complete closed-loop control logic.

[0239] The slurry circulation pump is the core energy-consuming equipment in the desulfurization system, except for the oxidation blower (accounting for 40%-50% of the total energy consumption of the desulfurization system). The core of its combination optimization model is to minimize energy consumption while ensuring desulfurization efficiency by rationally selecting the number of operating units and the combination method, based on the spray volume and coverage of the circulation pump, and at the same time adapting to real-time operating condition fluctuations (such as load and inlet SO2 concentration changes).

[0240] The online combination optimization system for slurry circulation pumps derives an optimized combination operation method for slurry circulation pumps based on the unit's real-time load, SO2 inlet and outlet concentrations, and over-limit conditions, using a slurry circulation pump combination optimization model.

[0241] The SO2 / pH dual-objective intelligent slurry supply system of this embodiment intelligently optimizes the SO2 of clean flue gas and uses the upper and lower limits of pH value as constraints. By introducing online parameters such as unit load, flue gas volume, inlet and outlet SO2, and slurry supply volume, the system uses a dynamic prediction model to respond to changes in inlet SO2 and load, controls pH value to stabilize, and achieves closed-loop control of clean flue gas SO2.

[0242] The method for building the combined optimization model of slurry circulation pumps is as follows:

[0243] Minimum necessary spray volume calculation

[0244] The relationship between spray volume and desulfurization efficiency follows the law of diminishing marginal returns; after the spray volume increases to a certain extent, the improvement in desulfurization efficiency slows down. The relationship between the two is fitted based on historical data.

[0245]

[0246] k 5 ,k 6 ,k 7 : Fit coefficient ( k 5 >0, increased spray volume promotes desulfurization; k 6 >0, increased pH enhances absorption; k 7 (Based on historical desulfurization efficiency fitting)

[0247] Export requirements must be met Concentration meets the standard, that is

[0248] (Inlet SO2 concentration > 35 mg / m³) 3 hour)

[0249] The minimum spray volume is obtained based on the target desulfurization efficiency:

[0250]

[0251] When the flue gas volume increases, the spray volume needs to be increased proportionally to ensure a stable gas-liquid ratio (spray volume / flue gas volume). Correction coefficient. Therefore:

[0252]

[0253] Pump combination flow rate and energy consumption calculation:

[0254] Assume the pump combination is as follows

[0255] (m≤N), then:

[0256] Total spray volume:

[0257] , Actual flow rate of a single pump

[0258] Total energy consumption:

[0259] ,in P i (Q i ) Calculations were made based on the power curve of the m-pump, and fitted with data from the manufacturer.

[0260] Sprinkler coverage constraints:

[0261]

[0262] When multiple pumps are running, the total coverage rate should avoid overlap and waste and have no blind spots. The total coverage rate is 1, minus the product of the areas not covered by each pump, to ensure that more than 95% of the flue gas cross section is covered by spraying.

[0263] Optimal pump combination selection:

[0264] In satisfying Q 总 ≥Q` 喷淋最小 , f 总 Under the premise of ≥95%, select total energy consumption. P 循环,总 Minimal combination:

[0265]

[0266] The above involves parameter definitions:

[0267] Flue gas parameters: Real-time flue gas volume Q 烟气 (m) 3 / h, positively correlated with unit load)

[0268] Inlet SO2 concentration (mg / m 3 )

[0269] flue gas temperature T 烟气 (℃ affects SO2 dissolution)

[0270] Slurry parameters: Slurry pH value (pH=5.5-6.0, SO2 absorption efficiency is optimal)

[0271] Slurry density: ρ 浆液 (kg / m 3 )

[0272] Equipment parameters:

[0273] Total number of circulating pumps N

[0274] Rated flow rate of a single pump Q 泵,额定 (m) 3 / h)

[0275] Single pump power curve P i (Q i ) (kW, flow rate) Q The actual power output is related to the head and efficiency.

[0276] Corresponding spray layer coverage f i (%, the percentage of flue gas cross-section covered when a single pump starts up);

[0277] The time interval between two adjacent pump combination switching is at least 15 minutes to reduce motor start-up and shutdown losses and system fluctuations;

[0278] If multiple pumps of the same model are operating, try to keep the flow rates of each pump close. For example, when two pumps are handling the total flow, each pump should operate at around 50% of its rated flow for the highest efficiency. When the slurry density increases, such as when the gypsum concentration increases, prioritize starting the pump with the higher head to avoid flow rate reduction. If the pH is high (>6.0), the spray volume can be appropriately reduced (due to increased absorption capacity) to reduce the number of pumps in operation. Conversely, if the pH is low, the spray volume must be ensured to be sufficient.

[0279] In conjunction with the oxidation air volume model: if the oxidation rate is insufficient and the desulfurization efficiency decreases, the spray volume needs to be appropriately increased through pump combination optimization compensation; conversely, if the oxidation is sufficient, the spray volume can be appropriately reduced to save energy; it can achieve a 10%-25% reduction in slurry circulation pump energy consumption compared to the traditional "fixed number of pumps operation" mode, while ensuring stable desulfurization efficiency.

[0280] Maintaining the SO2 concentration in the clean flue gas at the target value of ≤35mg / m³ is crucial, and the key parameter for this target is the pH value of the slurry. The pH value directly affects the final emission index by influencing the SO2 absorption efficiency (the absorption capacity drops sharply when the pH is too low, and may lead to limestone supersaturation when the pH is too high).

[0281] Increased unit load leads to increased flue gas volume, which in turn increases the total amount of SO2 entering the absorption tower per unit time, causing a sharp rise in inlet SO2 concentration. Under the same flue gas volume, the total SO2 volume surges, requiring stronger absorption capacity. This absorption capacity depends on pH and slurry supply rate. The limestone slurry supply rate is a direct means of adjusting the pH value: increasing the supply rate causes the Ca in the slurry to... 2+ As concentration increases, pH rises, enhancing the slurry's ability to neutralize acidity, and vice versa.

[0282] The SO2 / pH dual-objective intelligent dynamic prediction model for slurry supply is as follows:

[0283] SO2 Total Input Prediction

[0284] Total amount of SO2 entering the absorption tower per unit time

[0285]

[0286] Target pH calculation

[0287] Based on total SO2 input Based on the current absorption efficiency, the target pH value is obtained.

[0288]

[0289] k 8 ,k 9 ,k 10 The fitting coefficients are obtained from historical data. k 8 A value greater than 0 indicates that a higher pH level is required to increase the total amount of SO2. k 9 A value greater than 0 indicates an increase in circulation volume; therefore, the pH value should be appropriately lowered.

[0290] Q 循环 The slurry circulation spray volume of the circulating pump is the larger the circulation spray volume, the more sufficient the gas-liquid contact, and the lower the pH dependence.

[0291] Grout supply prediction

[0292] To maintain pH stability pH 目标 The slurry supply needs to be adjusted.

[0293]

[0294] ΔpH 历史 The correlation value between changes in slurry supply and pH in historical data.

[0295] k 11 The correction factor, taking into account slurry concentration and limestone activity, ranges from 1.1 to 1.3; in this embodiment, it is taken as 1.2.

[0296] The above involves parameter definitions.

[0297] flue gas volume Q 烟气 Inlet SO2 concentration The pH limit range is set to 5-6. Below 5, the absorption efficiency drops sharply, and above 6, it is easy to cause limestone supersaturation and scaling.

[0298] Closed-loop control process:

[0299] 1) Parameter acquisition and deviation calculation

[0300] Real-time comparison of SO2 concentration at the outlet Compliance value 35mg / m 3 Calculate the deviation

[0301] Simultaneously record the current pH value and pH 目标 deviation Δ pH ;

[0302] 2) Dynamic prediction and feedforward regulation

[0303] When the unit load fluctuates within ±10% or When the concentration rises sharply, the model predicts the change in the total SO2 input 5-10 minutes in advance, and calculates the required... pH 目标 It also outputs slurry supply adjustment commands to avoid large fluctuations in pH value;

[0304] 3) Feedback correction and stability control

[0305] If ΔC > 0, the exported SO2 exceeds the limit, and Δ pH If the pH is less than 0, increase the pulp supply until the pH reaches 0. Compliance;

[0306] If ΔC < 0, the exported SO2 is lower than the target, and Δ pH If the value is greater than 0, the amount of grout supplied should be reduced to avoid waste of limestone and a decrease in the purity of gypsum.

[0307] Slurry supply rate adjustment: Each adjustment should not exceed 15% of the current slurry supply to avoid drastic fluctuations in slurry concentration; if the energy-saving spray volume of the circulating pump is reduced, the pH value should be appropriately increased to compensate for the absorption capacity, i.e., to compensate for the slurry supply; conversely, the pH value can be decreased.

Claims

1. A desulfurization energy consumption optimization control system, characterized in that, include: An online measurement system for desulfurization slurry composition is used to monitor sulfite, pH, and ORP in the slurry in real time. The online measurement system for desulfurization slurry composition includes: a comprehensive sampling platform and an element measurement system; The integrated sampling platform is used for slurry sampling during system operation and automatically recirculates the slurry after measurement; the element measurement system is equipped with a sulfite meter, a pH meter, and an ORP meter. The oxidation air energy-saving closed-loop control system adopts the sulfite and oxidation rate indicators obtained in real time by the online measurement system of desulfurization slurry components, and obtains the oxidation fan operation strategy based on the oxidation air volume optimization model and the physical models of material consumption, energy consumption and emissions. The method for building the oxidation air volume optimization model is as follows: S1: Calculation of theoretical oxygen demand based on chemical reaction mechanism Existing oxidation demand: The total amount of unoxidized sulfite in the slurry is: ， The mass concentration of sulfite in the slurry (mg / m³) 3 V is the volume of slurry (m³) 3 ); Corresponding O2 demand: Incremental oxidation demand: SO2 in the flue gas is first converted into sulfite after entering the slurry, and the newly generated SO3 2- The rate is consistent with the SO2 removal rate: Exporting SO2 Inlet SO2 concentration Newly generated SO3 2- Corresponding O2 demand: Total oxygen demand: S2: Converts oxygen demand into air volume. Required air volume flow rate: (m) 3 / h), For the oxygen utilization rate of the fan; S3: Correction based on oxidation rate feedback Based on the current oxidation rate Dynamically adjust the theoretical air volume to ensure that the oxidation rate remains stable within the target range; like Increase airflow, correction factor ; like Reduce airflow, correction factor ; Ultimate optimal airflow: ； The online combination optimization system for slurry circulation pumps derives an optimized combination operation strategy for slurry circulation pumps based on the unit's real-time load, SO2 inlet and outlet concentrations, and over-limit conditions, using a slurry circulation pump combination optimization model. The SO2 / pH dual-objective intelligent slurry supply system intelligently optimizes the SO2 content of the flue gas and uses the upper and lower limits of the pH value as constraints. It employs a dynamic prediction model to respond to changes in inlet SO2 levels and load, thereby stabilizing the pH value and achieving closed-loop control of SO2 in the flue gas.

2. The desulfurization energy consumption optimization control system according to claim 1, characterized in that, The integrated sampling platform includes: The slurry sample return pipe has its inlet and outlet ends connected to the desulfurization tower and located below the surface of the desulfurization slurry. The inlet side of the slurry sample return pipe is a horizontal pipe section, and the outlet side is an inclined pipe section that slopes downwards. The horizontal pipe section and the inclined pipe section are connected by a vertical pipe section integrally formed. A slurry pump is installed on the horizontal pipe section; The element measurement system includes: a sulfite measuring instrument and its probe, a pH measuring instrument and its probe, and an ORP measuring instrument and its probe. The vertical pipe section is equipped with three sets of probe connectors at equal intervals; the three sets of probe connectors are arranged from top to bottom as follows: sulfite measuring instrument probe, pH measuring instrument probe, and ORP measuring instrument probe.

3. The desulfurization energy consumption optimization control system according to claim 1, characterized in that, The physical model for material consumption is for the consumption of desulfurizing agent, which is limestone. The limestone consumption model and its construction method are as follows: , meaning the amount of SO2 removed; k3 is the oxidation insufficiency correction factor; Gypsum moisture content model Moisture content of gypsum a and b are model fitting coefficients, obtained through different oxidation rates. The experimental data from the gypsum dehydration test determined a and b; when When W is at its minimum, which is 10%, then b = 10; When W=15%, then a=5 / 15 2 =0.022; Limestone consumption The gypsum moisture content W is maintained at the optimal value to keep the oxidation air volume at the optimal value, and the number of oxidation fans and power are automatically switched on and off based on the optimal oxidation air volume.

4. The desulfurization energy consumption optimization control system according to claim 1, characterized in that, The energy consumption physical model and its construction method are as follows: Oxidation blower power formula: 。 5. The desulfurization energy consumption optimization control system according to claim 1, characterized in that, Energy consumption correction model for switching on / off multiple oxidation blowers: Total energy consumption formula: P ； In the above formula, each parameter is defined as: n： Number of operating fans; N 切投 Number of times the ball is switched and thrown per unit of time; k 4 Start-stop energy consumption coefficient, set to 1.2 to cover additional losses.

6. The desulfurization energy consumption optimization control system according to claim 1, characterized in that, The emission physical model and its construction method are as follows: Desulfurization efficiency: coefficient c 1 -c 4 : c 1 By fitting historical oxidation rate data c 2 Fitting historical pH data of the slurry c 3 By fitting historical data of slurry flow rate c 4 The desulfurization efficiency was fitted using historical data; among which... c 1 For positive, c 2 Positive; oxidation rate ; Based on desulfurization efficiency The SO2 outlet concentration is: (mg / m 3 )。 7. The desulfurization energy consumption optimization control system according to claim 1, characterized in that, The method for building the combined optimization model of the slurry circulation pump is as follows: Minimum necessary spray volume calculation Desulfurization efficiency: The SO2 concentration at the export site must meet the standard, i.e. The minimum spray volume is obtained based on the target desulfurization efficiency: k 5 ,k 6 ,k 7 : Fit coefficient, k 5 >0, increased spray volume promotes desulfurization; k 6 >0, increased pH enhances absorption; k 7 Fitting historical desulfurization efficiency; When the flue gas volume increases, the spray volume needs to be increased proportionally to ensure a stable gas-liquid ratio; correction coefficient. Therefore: Pump combination flow rate and energy consumption calculation: Assume the pump combination is as follows (m≤N), where N is the total number of circulating pumps set, then: Total spray volume: , Q i Actual flow rate of a single pump Total energy consumption: ,in P i (Q i ) Calculations based on pump power curves; Sprinkler coverage constraints: Ensure that more than 95% of the flue gas cross-section is covered by spraying; Optimal pump combination selection: In satisfying Q 总 ≥Q` 喷淋最小 , f 总 Under the premise of ≥95%, select total energy consumption. P 循环,总 Minimal combination: 。 8. The desulfurization energy consumption optimization control system according to claim 1, characterized in that, The dynamic prediction model for the slurry supply volume in the SO2 / pH dual-objective intelligent slurry supply system is as follows: SO2 Total Input Prediction Total amount of SO2 entering the absorption tower per unit time Target pH calculation Based on total SO2 input Based on the current absorption efficiency, the target pH value is obtained. k 8 ,k 9 ,k 10 The fitting coefficients are obtained from historical data. k 8 A value greater than 0 indicates an increase in total SO2, requiring a higher pH level. k 9 A value greater than 0 indicates an increase in circulation volume; therefore, the pH value should be appropriately lowered. Grout supply prediction To maintain pH stability pH 目标 The slurry supply needs to be adjusted. ； k 11 The correction factor, taking into account slurry concentration and limestone activity, is taken as 1.1~1.

3.

9. The desulfurization energy consumption optimization control system according to claim 8, characterized in that, The upper and lower limits of pH are set to a range of 5 to 6.

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