Control system and method for solving blockage and scaling of desulfurization demister

Abstract

The invention discloses a control system and method for solving blockage and scaling of a desulfurization demister, and belongs to the technical field of limestone-gypsum wet flue gas desulfurization. According to the invention, the problem that the demister is blocked and scaled along with long-term operation of the existing desulfurization system is solved. A process water tank is connected with a gypsum dehydration system, a slurrying system and an absorption tower, an industrial water tank is connected with the gypsum dehydration system and a wastewater system, the gypsum dehydration system is connected with the slurrying system, the gypsum dehydration system and the slurrying system are connected with the absorption tower, and a demister flushing water recycling tank is connected into a pipeline for connecting the process water tank and a primary absorption tower. The primary absorption tower is connected with a demister flushing water recycling box, the demister flushing water recycling box is connected with a wastewater system, and the demister flushing water recycling box is connected to a pipeline for connecting the gypsum dehydration system and the wastewater system. The system and method for solving and controlling blockage and scaling of the desulfurization demister have good production and remarkable environmental protection benefits, safety benefits and economic benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of limestone-gypsum wet flue gas desulfurization, and specifically relates to a control system and method for solving the blockage and scaling of a desulfurization demister. Background Art

[0002] Limestone-gypsum wet flue gas desulfurization is the most widely used process for desulfurization in the coal-fired power industry. The demister is a key equipment in the wet desulfurization system. It is responsible for intercepting the droplets and particulate matter carried in the flue gas after the reaction, which can reduce the corrosion of downstream equipment and environmental pollution, such as "gypsum rain". The performance of the demister directly affects the energy consumption of the desulfurization system and even affects the safe and stable operation of the entire unit. At present, the bypass flue of the desulfurization system of coal-fired power generation units has been basically dismantled. Therefore, the performance of the demister is crucial to the stable operation of the desulfurization system and the unit.

[0003] At present, with the long-term operation of the desulfurization system, demister blockage and scaling problems often occur. The main reasons can be attributed to the following aspects: (1) demister performance. For the baffle demister, the demister blade spacing, blade type (such as whether hooks are installed) and number of channels have an important impact on its performance. In addition, the coverage rate and pressure of the flushing water also have a great impact on the operation of the demister. (2) Slurry quality. Different slurry densities, soluble salts and solid components have different requirements for flushing water. The actual operation flushing frequency and pressure are basically determined. When the slurry quality changes, it may cause scaling problems due to untimely flushing. (3) Flue gas flow rate. The flue gas flow rate directly affects the net surface flow rate of the demister, which in turn affects the demisting efficiency and droplet content. (4) Water balance control needs. Projects such as low-emission transformation of flue gas from coal-fired units (such as series-connected absorption towers), energy consumption improvement transformation (such as adding heat exchangers), and comprehensive utilization of water resources have been gradually implemented. On the one hand, the water consumption of the desulfurization system equipment has increased, and on the other hand, the amount of water discharged from the desulfurization system has been reduced. In order to meet the water balance requirements of the desulfurization system, the actual operation takes into account control requirements such as the absorption tower liquid level, which reduces the frequency of demister flushing, causing local blockage of the demister, which then spreads to the entire demister.

[0004] At present, the control and solution of demister blockage and scaling mainly adopts conventional means such as replacing the demister or further optimizing the slurry quality control level, but this method cannot fundamentally solve the problem, and this method is also difficult to adapt to the requirements of water balance control.

[0005] Therefore, the present application proposes a control system and method for solving the blockage and scaling of a desulfurization demister to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to solve the problem of blockage and scaling of the demister in the existing desulfurization system as it runs for a long time. A brief overview of the present invention is given below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to determine the key or important parts of the present invention, nor is it intended to limit the scope of the present invention.

[0007] The technical solution of the present invention:

[0008] Solution 1: A control system for solving the blockage and scaling of a desulfurization demister, comprising a process water tank, an industrial water tank, a gypsum dehydration system, a pulping system, a wastewater system, a demister flushing water recovery tank and an absorption tower. The process water tank is connected to the gypsum dehydration system, the pulping system and the absorption tower through multiple pipelines, the industrial water tank is connected to the gypsum dehydration system and the wastewater system through pipelines, the gypsum dehydration system is connected to the pulping system through pipelines, the gypsum dehydration system and the pulping system are connected to the absorption tower through pipelines, the absorption tower comprises a primary absorption tower and a secondary absorption tower, the primary absorption tower is connected to the secondary absorption tower through pipelines, the flue gas pipeline is connected to the primary absorption tower, the demister flushing water recovery tank is connected to the pipeline connecting the process water tank and the primary absorption tower through pipelines, the primary absorption tower is connected to the demister flushing water recovery tank through pipelines, the demister flushing water recovery tank is connected to the wastewater system through pipelines, and the demister flushing water recovery tank is connected to the pipeline connecting the gypsum dehydration system and the wastewater system through pipelines.

[0009] Furthermore, there is slurry at the bottom of the first-level absorption tower, and a first pressurized fan group, a spray pipe, a demister and a second pressurized fan group are arranged in sequence from bottom to top in the first-level absorption tower. The first pressurized fan group is arranged above the flue gas duct, the first pressurized fan group blows air from bottom to top, and the second pressurized fan group blows air from top to bottom.

[0010] Furthermore, the first pressurized fan group includes a plurality of pressurized fans and a round seat, the plurality of pressurized fans are evenly distributed on the round seat, the outer edge of the round seat is processed with drainage notches, and the plurality of drainage notches are evenly distributed on the circumference of the round seat.

[0011] Furthermore, the second pressurized fan group includes a plurality of pressurized fans and a round seat, the round seat is provided with a plurality of pressurized fans evenly distributed on the circumference thereof, and a smoke outlet is processed on the round seat.

[0012] Solution 2: A desulfurization demister blockage and scaling solution control method, which is based on the desulfurization demister blockage and scaling solution control system described in Solution 1 and includes the following steps:

[0013] Step 1: Analysis of the causes of demister blockage and scaling, including demister flue gas velocity adaptability test, scaling property analysis, and flushing water system inspection;

[0014] Step 2: Desulfurization system water balance model and demister numerical simulation, input desulfurization system boundary parameters, determine desulfurization system control objectives, give physical parameters and assumed parameters, calculate the desulfurization system inlet and outlet logistics components through logistics balance, calculate the desulfurization system inlet and outlet enthalpy through heat balance, calculate the desulfurization system heat balance relative error and compare it with the engineering setting error, and calculate the effective parameters in a cycle;

[0015] Step 3: Establish CFD simulation for flow field optimization of desulfurization system demister to obtain full three-dimensional detailed information of flow field inside desulfurization system demister, including velocity distribution, pressure distribution, droplet motion trajectory, and improve the design and optimize the structure of demister according to the three-dimensional detailed information;

[0016] Step 4: Multi-mechanism operation of water balance of desulfurization system. According to the actual operation logistics information of desulfurization system, the water balance system of desulfurization system is established. Combined with the water balance system model of desulfurization system, the actual distribution of water used in desulfurization system is given. According to the characteristics of recovered flushing water, the multi-mechanism operation mode of desulfurization water balance under typical working conditions is established. The demister flushing water recovery tank is used to flush the demister of the primary absorption tower, and the recovered flushing water is discharged to the wastewater system.

[0017] Furthermore, the step 1 is specifically as follows: the flue gas flow rate adaptability test refers to testing the flue gas flow rate, droplets, coordinated dust removal efficiency and desulfurization tower demister resistance at the demister inlet and the primary absorption tower outlet when the unit is running in hot state, and analyzing the adaptability of the existing desulfurization tower to the flue gas flow rate in combination with the design parameters;

[0018] The fouling property analysis refers to the analysis of fly ash, gypsum, slurry, limestone and demister flushing water before the absorption tower or after the demister when the unit is running hot, to determine the fouling properties of the demister;

[0019] Flushing water system inspection refers to reviewing historical data under cold conditions when the unit is shut down, comparing and analyzing the flushing water frequency or flushing water volume and flushing pressure before and after the demister is blocked, conducting cold tests on the flushing water system, and analyzing the operating status of the flushing water system.

[0020] Furthermore, the step 2 is specifically as follows:

[0021] The input boundary parameters of the desulfurization system include inlet flue gas temperature, flue gas temperature, inlet SO 2 concentration, volume fraction of flue gas components, ambient temperature, atmospheric pressure, and limestone purity. Control targets include total desulfurization efficiency, calcium-sulfur ratio, oxygen-sulfur ratio, average specific heat capacity of each logistics component, reaction enthalpy change, and relative error requirements of thermal balance required by the project;

[0022] Calculate the logistics components of inlet flue gas, oxidation air, and outlet flue gas, determine the process quantity of the desulfurization system in combination with the water content of the by-product gypsum and the wastewater volume of the desulfurization system, and calculate the limestone consumption and by-product gypsum volume of the desulfurization system;

[0023] Calculate the input heat of the desulfurization system, including the total enthalpy of the inlet flue gas, the total enthalpy of the oxidation air, the enthalpy of the limestone, the heat of reaction, and the enthalpy of the process water; calculate the output heat of the desulfurization system, including the total enthalpy of the outlet flue gas, the enthalpy of the by-product gypsum, the enthalpy of the desulfurization wastewater, and the heat dissipation;

[0024] Calculate the relative error of the thermal balance of the desulfurization system and compare it with the relative error requirement of the thermal balance to determine whether the assumed parameters are appropriate. Repeat the calculation until the required position is met.

[0025] Furthermore, the step three is specifically as follows:

[0026] The Euler-Lagrangian numerical simulation method of multiphase flow in the demister of the desulfurization system under typical working conditions is established. The flue gas flowing in the demister is regarded as a continuous phase, and its continuity equation, momentum equation and energy equation are constructed to solve the flue gas flow. The droplets carried in the flue gas are regarded as single spherical droplets, which are tracked separately using the Lagrangian method, and the balance equation of the force acting on the droplet particles is constructed to solve its motion trajectory and velocity. The demister of the desulfurization system is processed using a porous medium model to reduce the difficulty of mesh division and the amount of mesh calculation while meeting the calculation requirements.

[0027] CFD simulation is performed on the demister of the desulfurization system under typical working conditions to obtain its detailed flow field information, and the flow field velocity, pressure drop, and outlet droplet content information obtained by experimental measurement are compared and verified to ensure that the calculation model meets the engineering error requirements;

[0028] Carry out CFD numerical simulation of the desulfurization system demister under different load, inlet delayed flow, liquid-gas ratio, temperature and pressure operating conditions, introduce the flow field uniformity index to quantitatively characterize the uniformity of the flow field under different operating conditions, analyze the corresponding relationship between different control parameters and the key indicators of demister outlet droplet content and resistance performance, and determine the optimization matching principle between the desulfurization system demister performance and operating parameters;

[0029] The qualitative and quantitative effects of the demister blade spacing, blade type and number of channels in the desulfurization system on its flow field distribution, resistance characteristics and droplet movement are studied. CFD numerical simulations of demisters with different structural designs in a desulfurization system under typical operating conditions are carried out. The influence of its structural design on the flow field performance and the blockage structure area where droplets gather and entrain air are analyzed. An improved design scheme is proposed, and the CFD simulation is repeated using the optimized design parameters to verify the performance improvement.

[0030] The present invention has the following beneficial effects:

[0031] 1. A control system for solving blockage and scaling of a desulfurization demister of the present invention can obtain the water consumption distribution of the desulfurization system through a water balance model. On this basis, water cascade utilization and water-saving measures can be sought for each water use point. It is particularly suitable for the series connection process of multiple public systems in high-sulfur coal areas, has good production and significant environmental benefits, safety benefits and economic benefits, and has broad application prospects.

[0032] 2. A control system for solving the blockage and scaling of a desulfurization demister of the present invention has a first pressurized fan group arranged above the flue gas duct of the primary absorption tower, and a second pressurized fan group arranged above the demister. Under the convection impact of the first pressurized fan group and the second pressurized fan group, the mixing efficiency of the gas phase and the liquid phase in the spray pipe area is improved, and the efficiency of flue gas desulfurization is improved. At the same time, the second pressurized fan group arranged above the demister can also have a certain impact on the dirt attached to the demister, thereby reducing the blockage of the demister.

[0033] 3. The control method for solving the blockage and scaling of the desulfurization demister of the present invention is based on the demister flue gas velocity adaptability test, scale property analysis, and flushing water system inspection to establish a demister scale cause evaluation system to characterize the performance indicators that affect the operation of the demister. Focusing on the desulfurization system, based on the gas-liquid-solid three-phase logistics cycle of the desulfurization system, based on material balance and heat balance, a water balance correlation formula of the desulfurization system is established, and the key constraints of the water balance of the desulfurization system under typical working conditions are analyzed. Carry out CFD simulation work on the optimization of the demister flow field, and on this basis, develop a set of efficient and water-saving demister system to realize the recycling of demister flushing water, and simultaneously connect it with the pulping and wastewater systems. Furthermore, study the circulation characteristics of the demister flushing water recovery, combine with the actual operation of the desulfurization system, and realize the diversified and multi-directional utilization mechanism of flushing water, and then establish a new model of water balance for the desulfurization system.

[0034] 4. The present invention proposes an analysis method for the causes of scale formation in an absorber demister, which can be used for scaling analysis of demisters, absorber towers and other equipment in a limestone-gypsum wet flue gas desulfurization process, and further seeks suitable operation adjustment and transformation measures, such as gypsum scale - slurry, flue gas flow rate adaptability and demister performance factors, fly ash scale - dust collector, absorbent factors, sulfite - oxidizing air, slurry factors, and combined scale - comprehensive factors. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a system diagram of a control system for solving the blockage and scaling of desulfurization and mist eliminator;

[0036] Figure 2 It is the actual operation water balance logistics system diagram of the desulfurization system;

[0037] Figure 3 It is a schematic diagram of the structure of a primary absorption tower;

[0038] Figure 4 is a schematic diagram of the first pressurized fan group;

[0039] Figure 5 is a schematic diagram of the second pressurized fan group;

[0040] Figure 6 This is a flow chart of a method for solving the blockage and scaling of a desulfurization demister;

[0041] Figure 7 The present invention is a flow chart of step 2 of a control system for solving blockage and scaling of a desulfurization demister.

[0042] In the figure, 1-process water tank, 2-industrial water tank, 3-gypsum dehydration system, 4-pulping system, 5-wastewater system, 6-demister flushing water recovery tank, 7-primary absorption tower, 8-secondary absorption tower, 9-flue gas duct, 10-slurry, 11-spray pipe, 12-demister, 13-first pressurized fan group, 14-second pressurized fan group, 15-pressurized fan, 16-drainage gap, 17-flue gas outlet, 18-round seat. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0044] The connection mentioned in the present invention is divided into fixed connection and detachable connection. The fixed connection (i.e., non-detachable connection) includes but is not limited to conventional fixed connection methods such as folding connection, rivet connection, bonding connection and welding connection. The detachable connection includes but is not limited to conventional detachable methods such as threaded connection, snap connection, pin connection and hinge connection. When the specific connection method is not clearly defined, it is assumed that at least one connection method can always be found in the existing connection methods to achieve the function. Those skilled in the art can choose according to their needs. For example: welding connection is selected for fixed connection, and hinge connection is selected for detachable connection.

[0045] Embodiment 1, combination Figure 1-Figure 2The present embodiment is described. A control system for solving the blockage and scaling of a desulfurization demister in the present embodiment comprises a process water tank 1, an industrial water tank 2, a gypsum dehydration system 3, a pulping system 4, a wastewater system 5, a demister flushing water recovery tank 6 and an absorption tower. The process water tank 1 is connected to the gypsum dehydration system 3, the pulping system 4 and the absorption tower through a plurality of pipelines, the industrial water tank 2 is connected to the gypsum dehydration system 3 and the wastewater system 5 through pipelines, the gypsum dehydration system 3 is connected to the pulping system 4 through pipelines, and the gypsum dehydration system 3 and the pulping system 4 are connected through pipelines. It is connected to the absorption tower through a pipeline, and the absorption tower includes a primary absorption tower 7 and a secondary absorption tower 8. The primary absorption tower 7 is connected to the secondary absorption tower 8 through a pipeline, the flue gas duct 9 is connected to the primary absorption tower 7, the demister flushing water recovery tank 6 is connected to the pipeline connecting the process water tank 1 and the primary absorption tower 7 through a pipeline, the primary absorption tower 7 is connected to the demister flushing water recovery tank 6 through a pipeline, the demister flushing water recovery tank 6 is connected to the wastewater system 5 through a pipeline, and the demister flushing water recovery tank 6 is connected to the pipeline connecting the gypsum dehydration system 3 and the wastewater system 5 through a pipeline.

[0046] The main plant circulating water process water is injected into the process water tank 1, and the process water tank 1 injects process water into the gypsum dehydration system 3 through a pipeline, which is used for flushing the gypsum dehydration system 3 and the filter cloth. The process water tank 1 injects water into the pulping system 4 through another pipeline, which is used for flushing the pulping system 4, supplying water to the grinding head and the circulating box. The process water tank 1 injects water into the primary absorption tower 7 and the secondary absorption tower 8 of the absorption tower through a pipeline, which is used for flushing the primary absorption tower 7 and the secondary absorption tower 8 and flushing the demisters in the primary absorption tower 7 and the secondary absorption tower 8;

[0047] The industrial water system for the plant injects industrial water into the industrial water tank 2. The industrial water in the industrial water tank 2 is cooled by a vacuum pump and injected into the gypsum dehydration system 3. The filtrate water of the gypsum dehydration system 3 is input into the pulping system 4 through a pipeline. The wastewater generated in the gypsum dehydration system 3 is injected into the wastewater system 5 through a pipeline and finally discharged from the wastewater system 5.

[0048] The slurry in the gypsum dehydration system 3 and the pulping system 4 is respectively injected into the primary absorption tower 7 and the secondary absorption tower 8 through pipelines. The primary absorption tower 7 has the same structure as the secondary absorption tower 8. The flue gas enters the primary absorption tower 7 through the flue gas pipeline 9 for spray desulfurization. The flue gas discharged from the primary absorption tower 7 enters the secondary absorption tower 8 and is finally discharged from the secondary absorption tower 8 to the wet electrostatic precipitator. The flushing water of the wet electrostatic precipitator flows into the primary absorption tower 7 through the secondary absorption tower 8 and then is discharged into the gypsum dehydration system 3 through the primary absorption tower 7. The primary absorption tower 7 and the secondary absorption tower 8 are respectively connected to oxidation air pipelines. The oxidation air pipelines are filled with cooling water to provide sufficient oxidation air to the absorption towers and control the absorption towers within a suitable temperature range to avoid the influence of high temperature.

[0049] The demister flushing water recovery tank 6 is connected to the demister flushing pipeline connecting the process water tank 1 and the primary absorption tower 7 through a pipeline, thereby accelerating the flow rate in the demister flushing pipeline of the primary absorption tower 7, and accelerating the demister flushing pressure and efficiency of the primary absorption tower 7. The demister flushing water of the primary absorption tower 7 then flows into the demister flushing water recovery tank 6 through the pipeline, and the demister flushing water recovery tank 6 injects the wastewater into the wastewater system 5 through the pipeline. The demister flushing water recovery tank 6 is connected to the wastewater pipeline connecting the gypsum dehydration system 3 and the wastewater system 5 through another pipeline, thereby also increasing the medium flow rate of the pipeline and improving the wastewater discharge efficiency.

[0050] Embodiment 2, combined Figure 1-Figure 5 The present embodiment is described. The present embodiment is a control system for solving the blockage and scaling of a desulfurization demister. The difference from the embodiment 1 is that, based on the structure of the traditional absorption tower, the primary absorption tower 7 and the secondary absorption tower 8 are improved. The primary absorption tower 7 has the same structure as the secondary absorption tower 8. The bottom of the primary absorption tower 7 is a gypsum dehydration system 3, a pulping system 4 and a slurry 10 injected through the secondary absorption tower 8. A flue gas duct 9 is provided on the primary absorption tower 7. The flue gas duct 9 is arranged above the slurry 10. The flue gas enters the primary absorption tower 7 through the flue gas duct 9. The rising speed of the flue gas is increased by the first pressurized fan group 13. A multi-layer spray pipe 11 is arranged on the first pressurized fan 13. The liquid phase discharged from the spray pipe 11 is mixed with the gas phase of the flue gas to desulfurize the flue gas. The desulfurized flue gas is discharged after passing through the demister 12. A second pressurized fan group 14 is also arranged above the demister 12. The first pressurized fan group 13 increases the rising rate of the flue gas. The second pressurized fan group 14 is arranged opposite to the first pressurized fan group 13. The second pressurized fan group 14 blows air downward, so that the flue gas and the spray pipe 11 form a convection impact between the demister 12 and the first pressurized fan group 13, increasing the mixing of the gas phase and the liquid phase between the area and improving the desulfurization efficiency of the flue gas. At the same time, the second pressurized fan group 14 can blow off the dirt attached to the demister 12 in the process of blowing air downward to avoid clogging of the demister 12;

[0051] A total of 28 pressurized fans 15 are arranged on the round seat 18 of the first pressurized fan group 13, and 8 drainage notches 16 are processed on the circumference of the outer edge of the round seat 18 to increase the rising velocity of the flue gas without affecting the falling of the slurry. Eleven pressurized fans 15 are evenly distributed on the circumference of the round seat 18 of the second pressurized fan group 14, so the blowing pressure of the second pressurized fan group 14 is less than that of the first pressurized fan group 13. A flue gas outlet 17 is also processed on the round seat 18 of the second pressurized fan group 14, and the flue gas outlet 17 does not affect the discharge efficiency of the flue gas after desulfurization.

[0052] Embodiment 3, combined Figure 1-Figure 2 , Figure 6-Figure 7This embodiment is described. A method for controlling the blockage and scaling of a desulfurization demister in this embodiment includes the following steps:

[0053] Step 1: Analysis of the causes of blockage and scaling of the demister 12, including the flue gas velocity adaptability test of the demister 12, analysis of the properties of the scaling substances, and inspection of the flushing water system;

[0054] Step 2: numerical simulation of the water balance model of the desulfurization system and the demister 12, input the boundary parameters of the desulfurization system, determine the control target of the desulfurization system, give the physical parameters and assumed parameters, calculate the logistics components at the inlet and outlet of the desulfurization system through logistics balance, calculate the inlet and outlet enthalpy of the desulfurization system through heat balance, calculate the relative error of the heat balance of the desulfurization system and compare it with the engineering setting error, and calculate the effective parameters cyclically;

[0055] Step 3: Establish a CFD simulation for flow field optimization of the desulfurization system demister 12, obtain the full three-dimensional detailed information of the internal flow field of the desulfurization system demister 12, including velocity distribution, pressure distribution, and droplet motion trajectory, and improve the design and optimize the structure of the demister 12 based on the three-dimensional detailed information;

[0056] Step 4: Desulfurization system water balance multi-mechanism operation, according to the actual operation of the desulfurization system logistics information, as shown in the attached Figure 2 As shown, a desulfurization system water balance system is established. Combined with the desulfurization system water balance system model, the actual water distribution of the desulfurization system is given. According to the characteristics of the recovered flushing water, a desulfurization water balance multi-mechanism operation mode under typical working conditions is established. The demister flushing water recovery tank 6 is flushed to the demister 12 of the primary absorption tower 7, and the recovered flushing water is discharged to the wastewater system 5, as shown in the attached Figure 1 shown.

[0057] Specifically, in the step 1, the flue gas flow rate adaptability test refers to testing the flue gas flow rate, droplets, coordinated dust removal efficiency and desulfurization tower demister resistance at the inlet of the demister 12 and the outlet of the primary absorption tower 7 when the unit is running in a hot state, and analyzing the adaptability of the existing desulfurization tower to the flue gas flow rate in combination with the design parameters; the purpose of the flue gas flow rate adaptability test is to ensure that the flue gas flow rate is within the design range to reduce the carryover of droplets and reduce the sedimentation effect. The flue gas flow rate is measured at different heights and different time periods by an anemometer. The ideal flow rate range is between 1.5m / s and 3m / s. The actual measured flow rate is less than 1.5m / s, indicating that the amount of droplets carried away increases, which is easy to cause demister blockage. The actual measured flow rate is greater than 3m / s, indicating that the droplets are not fully removed, causing the problem of recirculation;

[0058] The scale property analysis refers to the analysis of fly ash, gypsum, slurry 10, limestone and demister flushing water before the absorption tower or after the demister 12 during hot operation of the unit to determine the scale properties of the demister 12; the scale collection is to collect scale samples inside the absorption tower and use scanning electron microscopy and energy spectrum analysis to analyze the composition. Common scale components include calcium salts, sulfates and organic matter. The density of scale is generally 1.5g / cm 3 ~2.5g / cm 3 The particle size of the scale is between 0.5 μm and 5 μm. The conclusion proves that the adhesion caused by high concentration of calcium salts and microorganisms is the main reason for the blockage of the demister 12.

[0059] Flushing water system inspection refers to reviewing historical data, comparing and analyzing the flushing water frequency or flushing water volume and flushing pressure before and after the demister 12 is blocked, conducting cold tests on the flushing water system, and analyzing the operating status of the flushing water system under cold conditions when the unit is shut down. The purpose of flushing water inspection is to confirm whether the quality and flow of flushing water are sufficient to remove scale, monitor the water quality of flushing water, including the pH value, turbidity and concentration of solution substances in flushing water, and measure the flow rate of flushing water. The pH value of flushing water is measured to be between 6.5 and 7.5. Turbidity greater than 50 NTU indicates that the turbidity exceeds the standard, affecting the cleaning effect. Dissolved solids greater than 1500 mg / L indicate that the flushing water is at a high concentration, affecting the flushing effect. The flushing flow rate is set at 8m 3 / h, less than 8m 3 / h indicates that the flushing flow rate is low, which affects the flushing effect and easily aggravates the blockage of the demister 12.

[0060] Specifically, the step 2 is specifically that the desulfurization system input boundary parameters include inlet flue gas temperature, flue gas temperature, inlet SO 2 concentration, volume fraction of flue gas components, ambient temperature, atmospheric pressure, and limestone purity. Control targets include total desulfurization efficiency, calcium-sulfur ratio, oxygen-sulfur ratio, average specific heat capacity of each logistics component, reaction enthalpy change, and relative error requirements of thermal balance required by the project;

[0061] Calculate the logistics components of inlet flue gas, oxidation air, and outlet flue gas, determine the process quantity of the desulfurization system in combination with the water content of the by-product gypsum and the wastewater volume of the desulfurization system, and calculate the limestone consumption and by-product gypsum volume of the desulfurization system;

[0062] Calculate the input heat of the desulfurization system, including the total enthalpy of the inlet flue gas, the total enthalpy of the oxidation air, the enthalpy of the limestone, the heat of reaction, and the enthalpy of the process water; calculate the output heat of the desulfurization system, including the total enthalpy of the outlet flue gas, the enthalpy of the by-product gypsum, the enthalpy of the desulfurization wastewater, and the heat dissipation;

[0063] Calculate the relative error of the thermal balance of the desulfurization system and compare it with the relative error requirement of the thermal balance to determine whether the assumed parameters are appropriate. Repeat the calculation until the required position is met.

[0064] Specifically, the step three is to establish a Euler-Lagrangian numerical simulation method for multiphase flow in a desulfurization system demister under typical working conditions, regard the flue gas flowing in the demister as a continuous phase, construct its continuity equation, momentum equation and energy equation to solve the flue gas flow, regard the droplets carried in the flue gas as single spherical droplets, use the Lagrangian method to track them separately, and construct the balance equation of the force acting on the droplet particles to solve their motion trajectory and velocity. The desulfurization system demister is processed using a porous medium model to reduce the difficulty of grid division and the amount of grid calculation while meeting the calculation requirements;

[0065] CFD simulation is performed on the demister of the desulfurization system under typical working conditions to obtain its detailed flow field information, and the flow field velocity, pressure drop, and outlet droplet content information obtained by experimental measurement are compared and verified to ensure that the calculation model meets the engineering error requirements;

[0066] Carry out CFD numerical simulation of the desulfurization system demister under different load, inlet delayed flow, liquid-gas ratio, temperature and pressure operating conditions, introduce the flow field uniformity index to quantitatively characterize the uniformity of the flow field under different operating conditions, analyze the corresponding relationship between different control parameters and the key indicators of demister outlet droplet content and resistance performance, and determine the optimization matching principle between the desulfurization system demister performance and operating parameters;

[0067] The qualitative and quantitative effects of the demister blade spacing, blade type and number of channels in the desulfurization system on its flow field distribution, resistance characteristics and droplet movement are studied. CFD numerical simulations of demisters with different structural designs in a desulfurization system under typical operating conditions are carried out. The influence of its structural design on the flow field performance and the blockage structure area where droplets gather and entrain air are analyzed. An improved design scheme is proposed, and the CFD simulation is repeated using the optimized design parameters to verify the performance improvement.

[0068] This embodiment is only an exemplary description of the present invention and does not limit its protection scope. Those skilled in the art may also make partial changes thereto, which are within the protection scope of the present invention as long as they do not exceed the spirit of the present invention.

Claims

1. A control system for solving the blockage and scaling of desulfurization mist eliminator, characterized by: The invention comprises a process water tank (1), an industrial water tank (2), a gypsum dehydration system (3), a pulping system (4), a wastewater system (5), a demister flushing water recovery tank (6) and an absorption tower. The process water tank (1) is respectively connected to the gypsum dehydration system (3), the pulping system (4) and the absorption tower through a plurality of pipelines. The industrial water tank (2) is respectively connected to the gypsum dehydration system (3) and the wastewater system (5) through pipelines. The gypsum dehydration system (3) and the pulping system (4) are respectively connected to the absorption tower through pipelines. The absorption tower comprises a The first-stage absorption tower (7) and the second-stage absorption tower (8) are connected via a pipeline, the flue gas pipeline (9) is connected to the first-stage absorption tower (7), the demister flushing water recovery tank (6) is connected to the pipeline connecting the process water tank (1) and the first-stage absorption tower (7) via a pipeline, the first-stage absorption tower (7) is connected to the demister flushing water recovery tank (6) via a pipeline, the demister flushing water recovery tank (6) is connected to the wastewater system (5) via a pipeline, and the demister flushing water recovery tank (6) is connected to the pipeline connecting the gypsum dehydration system (3) and the wastewater system (5) via a pipeline.

2. A desulfurization demister blockage and scaling solution control system according to claim 1, characterized in that: The bottom of the primary absorption tower (7) has a slurry (10), and the first pressure fan group (13), a spray pipe (11), a demister (12) and a second pressure fan group (14) are arranged in sequence from bottom to top in the primary absorption tower (7). The first pressure fan group (13) is arranged above the flue gas duct (9), the first pressure fan group (13) blows air from bottom to top, and the second pressure fan group (14) blows air from top to bottom.

3. A desulfurization demister blockage and scaling solution control system according to claim 2, characterized in that: The first pressurized fan group (13) comprises a plurality of pressurized fans (15) and a round seat (18), wherein the plurality of pressurized fans (15) are evenly distributed on the round seat (18), and a drainage notch (16) is processed on the outer edge of the round seat (18), and the plurality of drainage notches (16) are evenly distributed on the circumference of the round seat (18).

4. A desulfurization demister blockage and scaling solution control system according to claim 2, characterized in that: The second pressurized fan group (14) comprises a plurality of pressurized fans (15) and a round seat (18). The plurality of pressurized fans (15) are evenly distributed on the circumference of the round seat (18), and a smoke outlet (17) is processed on the round seat (18).

5. A desulfurization mist eliminator blockage and scaling solution control method, which is based on the desulfurization mist eliminator blockage and scaling solution control system according to claim 1, and is characterized in that: The following steps are involved: Step 1: Analyze the causes of blockage and scaling of the demister (12), including the flue gas velocity adaptability test of the demister (12), the scaling property analysis, and the flushing water system inspection; Step 2: numerically simulate the water balance model of the desulfurization system and the demister (12), input the boundary parameters of the desulfurization system, determine the control target of the desulfurization system, give the physical property parameters and the assumed parameters, calculate the logistics components at the inlet and outlet of the desulfurization system through logistics balance, calculate the inlet and outlet enthalpy values ​​of the desulfurization system through heat balance, calculate the relative error of the heat balance of the desulfurization system and compare it with the engineering setting error, and obtain the effective parameters through cyclic calculation; Step 3: Establish a CFD simulation for flow field optimization of the desulfurization system demister (12), obtain the full three-dimensional detailed information of the internal flow field of the desulfurization system demister (12), including flow velocity distribution, pressure distribution, and droplet motion trajectory, and improve the design and optimize the structure of the demister (12) according to the three-dimensional detailed information; Step 4: The desulfurization system water balance multi-mechanism operation is carried out. According to the actual operation logistics information of the desulfurization system, a desulfurization system water balance system is established. In combination with the desulfurization system water balance system model, the actual distribution of water used in the desulfurization system is given. According to the characteristics of the recovered flushing water, a desulfurization water balance multi-mechanism operation mode under typical working conditions is established. The demister (12) of the primary absorption tower (7) is flushed through the demister flushing water recovery tank (6), and the recovered flushing water is discharged to the wastewater system (5).

6. A method for controlling blockage and scaling of a desulfurization demister according to claim 5, characterized in that: The step 1 specifically includes: the flue gas flow rate adaptability test refers to testing the flue gas flow rate, droplets, coordinated dust removal efficiency and desulfurization tower desulfurization tower resistance at the inlet of the demister (12) and the outlet of the primary absorption tower (7) when the unit is in hot operation, and analyzing the adaptability of the existing desulfurization tower to the flue gas flow rate in combination with the design parameters; The fouling property analysis refers to taking fly ash, gypsum, slurry (10), limestone and demister flushing water before the absorption tower or after the demister (12) for chemical analysis when the unit is in hot operation, so as to determine the fouling properties of the demister (12); The flushing water system inspection refers to the process of reviewing historical data, comparing and analyzing the flushing water frequency or flushing water volume and flushing pressure before and after the demister (12) is blocked, conducting a cold test of the flushing water system, and analyzing the operating status of the flushing water system under the cold condition of the unit being shut down.

7. A method for controlling blockage and scaling of a desulfurization demister according to claim 5, characterized in that: The step 2 is specifically as follows: The input boundary parameters of the desulfurization system include inlet flue gas temperature, flue gas temperature, inlet SO 2 concentration, volume fraction of flue gas components, ambient temperature, atmospheric pressure, and limestone purity. Control targets include total desulfurization efficiency, calcium-sulfur ratio, oxygen-sulfur ratio, average specific heat capacity of each logistics component, reaction enthalpy change, and relative error requirements of thermal balance required by the project; Calculate the logistics components of inlet flue gas, oxidation air, and outlet flue gas, determine the process quantity of the desulfurization system in combination with the water content of the by-product gypsum and the wastewater volume of the desulfurization system, and calculate the limestone consumption and by-product gypsum volume of the desulfurization system; Calculate the input heat of the desulfurization system, including the total enthalpy of the inlet flue gas, the total enthalpy of the oxidation air, the enthalpy of the limestone, the heat of reaction, and the enthalpy of the process water; calculate the output heat of the desulfurization system, including the total enthalpy of the outlet flue gas, the enthalpy of the by-product gypsum, the enthalpy of the desulfurization wastewater, and the heat dissipation; Calculate the relative error of the thermal balance of the desulfurization system and compare it with the relative error requirement of the thermal balance to determine whether the assumed parameters are appropriate. Repeat the calculation until the required position is met.

8. A method for controlling blockage and scaling of a desulfurization demister according to claim 5, characterized in that: The step three is specifically as follows: The Euler-Lagrangian numerical simulation method of multiphase flow in the demister of the desulfurization system under typical working conditions is established. The flue gas flowing in the demister is regarded as a continuous phase, and its continuity equation, momentum equation and energy equation are constructed to solve the flue gas flow. The droplets carried in the flue gas are regarded as single spherical droplets, which are tracked separately using the Lagrangian method, and the balance equation of the force acting on the droplet particles is constructed to solve its motion trajectory and velocity. The demister of the desulfurization system is processed using a porous medium model to reduce the difficulty of mesh division and the amount of mesh calculation while meeting the calculation requirements. CFD simulation is performed on the demister of the desulfurization system under typical working conditions to obtain its detailed flow field information, and the flow field velocity, pressure drop, and outlet droplet content information obtained by experimental measurement are compared and verified to ensure that the calculation model meets the engineering error requirements; Carry out CFD numerical simulation of the desulfurization system demister under different load, inlet delayed flow, liquid-gas ratio, temperature and pressure operating conditions, introduce the flow field uniformity index to quantitatively characterize the uniformity of the flow field under different operating conditions, analyze the corresponding relationship between different control parameters and the key indicators of demister outlet droplet content and resistance performance, and determine the optimization matching principle between the desulfurization system demister performance and operating parameters; The qualitative and quantitative effects of the demister blade spacing, blade type and number of channels in the desulfurization system on its flow field distribution, resistance characteristics and droplet movement are studied. CFD numerical simulations of demisters with different structural designs in a desulfurization system under typical operating conditions are carried out. The influence of its structural design on the flow field performance and the blockage structure area where droplets gather and entrain air are analyzed. An improved design scheme is proposed, and the CFD simulation is repeated using the optimized design parameters to verify the performance improvement.

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