A control system and method for desulfurization mist eliminator plugging and fouling resolution

Abstract

The application relates to a desulfurization and demister blocking and scaling solution control system and method, belonging to the technical field of limestone-gypsum wet flue gas desulfurization. The application solves the problem that the existing desulfurization system is blocked and scaled with long-term operation. The process water tank is connected with a gypsum dehydration system, a pulping system and an absorption tower; the industrial water tank is connected with the gypsum dehydration system and a wastewater system; the gypsum dehydration system is connected with the pulping system; the gypsum dehydration system and the pulping system are connected with the absorption tower; the demister flushing water recovery tank is connected with the pipeline connecting the process water tank and the primary absorption tower; the primary absorption tower is connected with the demister flushing water recovery tank; the demister flushing water recovery tank is connected with the wastewater system; and the demister flushing water recovery tank is connected with the pipeline connecting the gypsum dehydration system and the wastewater system. The desulfurization and demister blocking and scaling solution control system and method have good production, remarkable environmental protection benefits, safety benefits and economic benefits.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of limestone-gypsum wet flue gas desulfurization, and particularly relates to a desulfurization and demister blockage and scaling solution control system and method. BACKGROUND

[0002] Limestone-gypsum wet flue gas desulfurization is the most widely used process in the coal power industry at present, and the demister is the key equipment of the wet desulfurization system, which plays a role in intercepting the droplets and particulate matters carried in the flue gas after reaction, and 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 the coal-fired power generation unit is basically removed, and 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, the problems of demister blockage and scaling occur from time to time, and the main reasons can be summarized as follows: (1) demister performance, for the baffle demister, the blade spacing, blade type (such as whether to install a hook piece) and the number of passages all have important influence on the performance. In addition, the washing water coverage and pressure also have great influence on the operation of the demister. (2) slurry quality, different slurry density, soluble salt and solid phase components have different requirements for washing water, and when the slurry quality changes, the scaling problem caused by the delay of washing may occur. (3) flue gas flow rate, the flue gas flow rate directly affects the net face flow rate of the demister, and further affects the demisting efficiency and droplet content. (4) water balance control requirement, the low emission transformation (such as series absorption tower) of flue gas of coal-fired units, the energy consumption improvement transformation (such as the addition of heat exchanger), and the comprehensive utilization of water resources and other projects are gradually implemented, which on the one hand increases the water consumption of the desulfurization system equipment, and on the other hand reduces the water discharge of the desulfurization system. In order to meet the water balance requirement of the desulfurization system, the control requirements such as the liquid level of the absorption tower are considered in the actual operation, so that the washing frequency of the demister is reduced, causing local blockage of the demister, and further spreading to the entire demister.

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

[0005] Therefore, the application provides a desulfurization and demister blockage and scaling solution control system and method to solve the above problems. SUMMARY

[0006] The present application is developed to solve the problem of blockage and scaling of the demister in the existing desulfurization system with long-term operation. In the following, a brief summary of the present application is given to provide a basic understanding of some aspects of the present application. It should be understood that this summary is not an exhaustive overview of the present application. It is not intended to determine the key or important parts of the present application, nor to limit the scope of the present application.

[0007] Technical scheme of the present application:

[0008] Solution one: a desulfurization and demister blockage and scaling control system, comprising a process water tank, an industrial water tank, a gypsum dehydration system, a pulp making system, a wastewater system, a demister flushing water recovery tank and an absorption tower, the process water tank is connected with the gypsum dehydration system, the pulp making system and the absorption tower through multiple pipelines, the industrial water tank is connected with the gypsum dehydration system and the wastewater system through pipelines, the gypsum dehydration system is connected with the pulp making system through a pipeline, the gypsum dehydration system and the pulp making system are connected with the absorption tower through pipelines, the absorption tower comprises a primary absorption tower and a secondary absorption tower, the primary absorption tower is connected with the secondary absorption tower through a pipeline, a flue gas pipeline is connected with the primary absorption tower, the demister flushing water recovery tank is connected with the pipeline connecting the process water tank and the primary absorption tower through a pipeline, the primary absorption tower is connected with the demister flushing water recovery tank through a pipeline, the demister flushing water recovery tank is connected with the wastewater system through a pipeline, and the demister flushing water recovery tank is connected with the pipeline connecting the gypsum dehydration system and the wastewater system through a pipeline.

[0009] Further, the bottom of the primary absorption tower has slurry, the primary absorption tower is sequentially provided with a first pressurized fan group, a spray pipe, a demister and a second pressurized fan group from bottom to top, the first pressurized fan group is arranged above the flue gas pipeline, the first pressurized fan group blows from bottom to top, and the second pressurized fan group blows from top to bottom.

[0010] Further, the first pressurized fan group comprises multiple pressurized fans and a circular seat, the circular seat is uniformly provided with multiple pressurized fans, the outer edge of the circular seat is processed with a liquid discharge notch, and multiple liquid discharge notches are circumferentially distributed on the circular seat.

[0011] Further, the second pressurized fan group comprises multiple pressurized fans and a circular seat, the circular seat is circumferentially provided with multiple pressurized fans, and the circular seat is processed with a flue gas outlet.

[0012] Solution two: a desulfurization and demister blockage and scaling control method, which is realized based on the desulfurization and demister blockage and scaling control system of solution one, and comprises the following steps:

[0013] Step one: analysis of the causes of demister blockage and scaling, comprising demister flue gas flow rate adaptability test, scale property analysis and flushing water system inspection;

[0014] Step two: desulfurization system water balance model and demister numerical simulation, input desulfurization system boundary parameters, determine the desulfurization system control target, give the physical property parameters and the assumed parameters, calculate the desulfurization system inlet and outlet stream components through stream balance, calculate the desulfurization system inlet and outlet enthalpy through heat balance, calculate the relative error of desulfurization system heat balance and compare with the engineering set error, and the effective parameters are obtained through cyclic calculation;

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

[0016] Step four: desulfurization system water balance multi-mechanism operation, according to the actual running stream information of desulfurization system, establish desulfurization system water balance system, give the actual distribution of desulfurization system water, according to the characteristics of recycled washing water, establish desulfurization water balance multi-mechanism operation mode under typical working conditions, through demister flushing water recovery tank to primary absorption tower demister flushing, recycled washing water is discharged to wastewater system.

[0017] Further, the step one is specifically: the flue gas flow rate adaptability test refers to testing the flue gas flow, droplet, synergistic dust removal efficiency and desulfurization tower demister resistance at the inlet of demister and the outlet of primary absorption tower when the unit is in hot state operation, and analyzing the adaptability of existing desulfurization tower to flue gas flow rate in combination with design parameters;

[0018] The scale property analysis refers to taking fly ash, gypsum, slurry, limestone and demister flushing water before the absorption tower or after the demister for chemical analysis when the unit is in hot state operation, and determining the scale property of demister;

[0019] The flushing water system inspection refers to reviewing historical data, comparing and analyzing flushing water frequency or flushing water volume, flushing pressure before and after demister blockage under the condition of unit shutdown and cold state, carrying out flushing water system cold state test, and analyzing the operation status of flushing water system.

[0020] Further, the step two is specifically:

[0021] The input boundary parameters of desulfurization system include inlet flue gas temperature, flue gas temperature, inlet SO 2 Concentration, flue gas component volume fraction, ambient temperature, atmospheric pressure, limestone purity, control target includes total desulfurization efficiency, calcium sulfur ratio, oxygen sulfur ratio, average specific heat capacity of each stream component, reaction enthalpy change and engineering required to meet the relative error requirement of heat balance;

[0022] The components of each flow of inlet flue gas, oxidizing air, outlet flue gas are calculated, combined with the water content of byproduct gypsum and the waste water amount of the desulfurization system, the process amount of the desulfurization system is determined, the limestone consumption and the byproduct gypsum amount of the desulfurization system are calculated;

[0023] The input heat of the desulfurization system is calculated, including the total enthalpy value of inlet flue gas, the total enthalpy value of oxidizing air, the enthalpy value of limestone, reaction heat and the enthalpy value of process water, and the output heat of the desulfurization system is calculated, including the total enthalpy value of outlet flue gas, the enthalpy value of byproduct gypsum, the enthalpy value of desulfurization waste water and heat dissipation amount;

[0024] The relative error of the heat balance of the desulfurization system is calculated, and compared with the requirement of the relative error of the heat balance, whether the assumed parameters are suitable is determined, and the calculation is repeated until the requirement is met.

[0025] Further, the step three is specifically:

[0026] A multi-phase flow Euler-Lagrange numerical simulation method of a demister in a typical working condition desulfurization system is established, the flue gas flowing in the demister is regarded as a continuous phase, continuity equation, momentum equation and energy equation thereof are constructed to solve the flue gas flow, the fog droplets carried in the flue gas are regarded as single spherical droplets, the Lagrange method is adopted to track the fog droplets respectively, the balance equation of the force acting on the fog droplet particles is constructed to solve the motion track and speed thereof, the demister in the desulfurization system is processed by using a porous medium model, the grid division difficulty and grid calculation amount are reduced under the condition of meeting the calculation requirement;

[0027] The CFD simulation is carried out on the demister in the typical working condition desulfurization system to obtain detailed flow field information, and the flow field flow velocity, pressure drop and outlet droplet content information obtained by experiment measurement are compared and verified, so that the calculation model meets the engineering error requirement;

[0028] The CFD numerical simulation of the demister in the desulfurization system under different load, inlet delay flow, liquid-gas ratio, temperature and pressure operating conditions is carried out, the flow field uniformity index is introduced to quantitatively characterize the uniformity of the flow field under different operating conditions, the corresponding relationship between different regulation parameters and the key indicators of the outlet droplet content and resistance performance of the demister is analyzed, and the optimization matching principle between the performance of the demister in the desulfurization system and the operating parameters is determined;

[0029] The qualitative and quantitative influence of the blade spacing, blade type and channel number of the demister in the desulfurization system on the flow field distribution, resistance characteristics and fog droplet motion is researched, the CFD numerical simulation of the demister with different structural designs in the typical working condition desulfurization system is carried out, the influence of the mechanism design on the flow field performance is analyzed, the blocking structure area of the fog droplet aggregation induced air is proposed, and the improved design scheme is repeatedly used for CFD simulation by using the optimized design parameters, and the performance improvement is verified.

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

[0031] 1. The desulfurization and mist eliminator blockage and scaling solution control system of the present application can obtain water distribution of the desulfurization system through a water balance model, and can seek water gradient utilization and water saving measures for each water point, especially suitable for the series process of high-sulfur coal regional multi-public system, has good production, significant environmental protection, safety and economic benefits, and has wide application prospect.

[0032] 2. The desulfurization and mist eliminator blockage and scaling solution control system of the present application is provided with a first pressurized fan group above the flue gas pipeline of the primary absorption tower, and a second pressurized fan group above the mist eliminator, under the counterflow 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, and the second pressurized fan group arranged above the mist eliminator can also form a certain impact on the dirt attached to the mist eliminator, reducing the blockage of the mist eliminator.

[0033] 3. The desulfurization and mist eliminator blockage and scaling solution control method of the present application establishes a mist eliminator dirt cause evaluation system to represent the performance index affecting the operating condition of the mist eliminator according to the mist eliminator flue gas flow rate adaptability test, dirt attribute analysis and flushing water system inspection. Focus on the desulfurization system, based on the gas-liquid-solid three-phase material flow circulation of the desulfurization system, the desulfurization system water balance correlation is established based on material balance and heat balance, and the key factors restricting the water balance of the desulfurization system under typical working conditions are analyzed. Develop a set of high-efficiency water-saving mist elimination system based on the CFD simulation of the mist eliminator flow field, realize the recycling of the mist eliminator flushing water, and synchronize with the pulp and wastewater system. Further, research the recycling characteristics of the mist eliminator recovery flushing water, combine with the actual operation of the desulfurization system, realize the diversified and multi-directional utilization mechanism of the flushing water, and then establish a new mode of water balance of the desulfurization system.

[0034] 4. The present application proposes an absorption tower mist eliminator dirt cause analysis method, which can be used for scaling analysis of mist eliminator, absorption tower and other equipment in limestone-gypsum wet desulfurization process, and then seek suitable operation adjustment and modification measures, such as gypsum scale dirt-sluury, flue gas flow rate adaptability and mist eliminator performance factors, fly ash dirt-dust collector and absorbent factors, sulfite-oxidizing air and slurry factors, and combined dirt-comprehensive factors. BRIEF DESCRIPTION OF DRAWINGS

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

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

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

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

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

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

[0041] Figure 7 is a flow chart of step two of a control system for solving the blockage and scaling of a desulfurization and demister.

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

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

[0044] The connection mentioned in the present application 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 flange connection, rivet connection, adhesive connection and welding connection. The detachable connection includes but is not limited to conventional detachable methods such as threaded connection, buckle connection, pin connection and hinge connection. When the specific connection method is not explicitly limited, it is assumed that at least one connection method can be found in the existing connection methods to achieve the function. The person skilled in the art can choose as needed. For example: the fixed connection selects welding connection, and the detachable connection selects hinge connection.

[0045] Example 1, in combination Figures 1-2To illustrate the embodiment, the embodiment is a kind of desulfurization demister blockage, scale solution control system, including process water tank 1, industrial water tank 2, gypsum dehydration system 3, pulping system 4, waste water system 5, demister flush water recovery tank 6 and absorption tower, process water tank 1 is connected with gypsum dehydration system 3, pulping system 4 and absorption tower respectively by multiple pipelines, industrial water tank 2 is connected with gypsum dehydration system 3 and waste water system 5 by pipeline, gypsum dehydration system 3 is connected with pulping system 4 by pipeline, gypsum dehydration system 3 and pulping system 4 are connected with absorption tower by pipeline respectively, absorption tower includes primary absorption tower 7 and secondary absorption tower 8, primary absorption tower 7 is connected with secondary absorption tower 8 by pipeline, flue gas pipeline 9 is connected with primary absorption tower 7, demister flush water recovery tank 6 is connected on the pipeline of process water tank 1 and primary absorption tower 7 by pipeline, primary absorption tower 7 is connected with demister flush water recovery tank 6 by pipeline, demister flush water recovery tank 6 is connected with waste water system 5 by pipeline, demister flush water recovery tank 6 is connected on the pipeline of gypsum dehydration system 3 and waste water system 5 by pipeline.

[0046] Main plant circulating water process water is injected into process water tank 1, process water tank 1 injects process water into gypsum dehydration system 3 through pipeline, for the flushing of gypsum dehydration system 3 and filter cloth flushing, process water tank 1 injects water into pulping system 4 through another pipeline, for the flushing of pulping system 4, mill head water supply and circulating tank water supply, process water tank 1 injects water into the primary absorption tower 7 and secondary absorption tower 8 of absorption tower through pipeline, for the flushing of primary absorption tower 7 and secondary absorption tower 8 and the flushing of demister in primary absorption tower 7 and secondary absorption tower 8;

[0047] Plant industrial water system injects industrial water into industrial water tank 2, and the industrial water of industrial water tank 2 is injected into gypsum dehydration system 3 by vacuum pump cooling, and the filtrate water of gypsum dehydration system 3 is input into pulping system 4 through pipeline, and the waste water generated in gypsum dehydration system 3 is injected into waste water system 5 through pipeline, and finally discharged by waste water system 5;

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

[0049] The demister flushing water recovery tank 6 is connected to the demister flushing pipeline of the first absorption tower 7 through a pipeline connected to the process water tank 1, so as to accelerate the flow rate in the demister flushing pipeline of the first absorption tower 7, accelerate the demister flushing pressure and efficiency of the first absorption tower 7, and flow the demister flushing water of the first absorption tower 7 into the demister flushing water recovery tank 6. The demister flushing water recovery tank 6 injects the waste water into the waste water system 5 through a pipeline, and the demister flushing water recovery tank 6 is connected to the waste water pipeline of the gypsum dehydration system 3 and the waste water system 5 through another pipeline, so as to also increase the medium flow rate of the pipeline and improve the waste water discharge efficiency.

[0050] Embodiment 2, in combination with Figures 1-5 In this embodiment, the difference between the desulfurization and demisting device and the control system for solving the blockage and scaling of the device and embodiment 1 is that the first absorption tower 7 and the second absorption tower 8 are improved on the basis of the traditional absorption tower structure. The first absorption tower 7 and the second absorption tower 8 have the same structure. The bottom of the first absorption tower 7 is connected to the gypsum dehydration system 3, the pulp preparation system 4, and the slurry 10 injected through the second absorption tower 8. The first absorption tower 7 is provided with a flue gas pipeline 9 arranged above the slurry 10. The flue gas enters the first absorption tower 7 through the flue gas pipeline 9. The first pressurized fan group 13 increases the rising rate of the flue gas. A plurality of spray pipes 11 are arranged on the first pressurized fan 13. The liquid phase discharged from the spray pipes 11 mixes with the gas phase of the flue gas to desulfurize the flue gas. After desulfurization, the flue gas is discharged after passing through the demister 12. The second pressurized fan group 14 is 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 downward to form a countercurrent impact between the demister 12 and the first pressurized fan group 13, increase the mixing of the gas phase and the liquid phase between the regions, and improve the desulfurization efficiency of the flue gas. At the same time, the second pressurized fan group 14 blows off the dirt attached to the demister 12 during the downward blowing process, thereby avoiding the blockage of the demister 12.

[0051] There are 28 pressurized fans 15 arranged on the circular seat 18 of the first pressurized fan group 13. Eight liquid discharge notches 16 are circumferentially processed on the outer edge of the circular seat 18 to increase the rising flow rate of the flue gas without affecting the falling of the slurry. There are 11 pressurized fans 15 circumferentially distributed on the circular 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 processed on the circular seat 18 of the second pressurized fan group 14, which does not affect the discharge efficiency of the desulfurized flue gas under the action of the flue gas outlet 17.

[0052] Embodiment 3, in combination with Figures 1-2 , Figures 6-7To illustrate the embodiments, the desulfurization and mist eliminator blockage and scaling solution control method of the embodiments includes the following steps:

[0053] Step one: analysis of the causes of the blockage and scaling of the mist eliminator 12, including mist eliminator 12 flue gas flow rate adaptability testing, scale attribute analysis, and flush water system inspection;

[0054] Step two: desulfurization system water balance model and mist eliminator 12 numerical simulation, input desulfurization system boundary parameters, determine desulfurization system control targets, give physical property parameters and assumed parameters, calculate the inlet and outlet stream components of the desulfurization system through stream balance, calculate the inlet and outlet enthalpy values of the desulfurization system through heat balance, calculate the relative error of the desulfurization system heat balance and compare it with the engineering set error, and cyclically calculate the effective parameters;

[0055] Step three: establish a desulfurization system mist eliminator 12 flow field optimization CFD simulation to obtain detailed three-dimensional information of the internal flow field of the desulfurization system mist eliminator 12, including flow rate distribution, pressure distribution, and droplet motion trajectory, and improve the design and optimize the structure of the mist eliminator 12 based on the three-dimensional detailed information;

[0056] Step four: desulfurization system water balance multi-mechanism operation, according to the actual stream information of the desulfurization system, such as the accompanying Figure 2 , establish a desulfurization system water balance system, combine the desulfurization system water balance system model, give the actual distribution of water in the desulfurization system, establish a desulfurization water balance multi-mechanism operation mode under typical working conditions according to the characteristics of the recovered flush water, and through the mist eliminator flush water recovery tank 6 to the mist eliminator 12 of the primary absorption tower 7, the recovered flush water is discharged to the wastewater system 5, as shown in the accompanying Figure 1 .

[0057] Specifically, in step one, the flue gas flow rate adaptability test refers to testing the flue gas flow rate, droplets, synergistic dust removal efficiency, and desulfurization tower mist eliminator resistance at the inlet of the mist eliminator 12 and the outlet of the primary absorption tower 7 during the hot state operation of the unit, combining the design parameters to analyze the adaptability of the existing desulfurization tower to the flue gas flow rate; 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 droplet carryover and reduce the settling 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 1.5 m / s and 3 m / s, the actual measured flow rate less than 1.5 m / s indicates that the amount of droplet carryover increases, which easily causes the blockage of the mist eliminator, and the actual measured flow rate greater than 3 m / s indicates that the droplets are not fully removed, causing recirculation problems;

[0058] The scale property analysis refers to taking the fly ash, gypsum, slurry 10, limestone and demister flush water after the demister 12 for chemical analysis to determine the scale property of the demister 12 when the unit is in hot state operation. The scale is collected inside the absorption tower, and the composition analysis is performed by using a scanning electron microscope and energy spectrum analysis. The common scale compositions include calcium salt, sulfate and organic matter. The density of the scale is generally between 1.5 g / cm 3 ~ 2.5 g / cm 3 , and the scale particle size is between 0.5 μm and 5 μm. The conclusion proves that the high concentration of calcium salt and the adhesion caused by microorganisms are the main reasons for the blockage of the demister 12.

[0059] The flush water system inspection refers to checking the historical data, comparing and analyzing the flush water frequency or flush water volume, flush pressure before and after the blockage of the demister 12, carrying out the cold state test of the flush water system, and analyzing the operation condition of the flush water system under the cold state condition of the unit shutdown. The purpose of the flush water inspection is to confirm whether the quality and flow of the flush water are sufficient to remove the scale. The water quality monitoring of the flush water includes the detection of the pH value, turbidity and solution substance concentration of the flush water, and the measurement of the flow of the flush water. The measured pH value of the flush water is between 6.5 and 7.5. The turbidity greater than 50 NTU indicates that the turbidity is out of standard and affects the cleaning effect. The dissolved solid greater than 1500 mg / L indicates that the flush water is in high concentration and affects the flush effect. The flush flow is set to 8 m 3 / h. The flush flow less than 8 m 3 / h indicates that the flush flow is low and affects the flush effect, which easily aggravates the blockage of the demister 12.

[0060] Specifically, the step two is specifically to input boundary parameters of the desulfurization system, including inlet flue gas temperature, flue gas temperature, inlet SO 2 concentration, flue gas component volume fraction, ambient temperature, atmospheric pressure, limestone purity, control targets including total desulfurization efficiency, calcium-sulfur ratio, oxygen-sulfur ratio, average specific heat capacity of each stream component, reaction enthalpy change and engineering required to meet the relative error requirement of heat balance.

[0061] The inlet flue gas, oxidizing air and outlet flue gas are calculated, and the water content of the byproduct gypsum and the wastewater amount of the desulfurization system are combined to determine the process amount of the desulfurization system, and the limestone consumption and the byproduct gypsum amount of the desulfurization system are calculated.

[0062] The input heat of the desulfurization system is calculated, including the total enthalpy value of the inlet flue gas, the total enthalpy value of the oxidizing air, the enthalpy value of the limestone, the reaction heat and the enthalpy value of the process water. The output heat of the desulfurization system is calculated, including the total enthalpy value of the outlet flue gas, the enthalpy value of the byproduct gypsum, the enthalpy value of the desulfurization wastewater and the heat dissipation amount.

[0063] The relative error of the thermal balance of the desulfurization system is calculated, and compared with the requirement of the relative error of the thermal balance to determine whether the assumed parameters are appropriate, and the calculation is repeated until the requirement position is met.

[0064] Specifically, the step three is specifically establishing a multiphase flow Euler-Lagrange numerical simulation method for a demister in a typical working condition desulfurization system, regarding the flue gas flowing in the demister as a continuous phase, constructing continuity equation, momentum equation and energy equation for solving the flue gas flow, regarding the droplets carried in the flue gas as single spherical droplets, tracking the droplets by using the Lagrange method, constructing a balance equation of forces acting on the droplets to solve the motion trajectory and velocity of the droplets, and using a porous medium model to process the demister in the desulfurization system, reducing the difficulty of grid division and grid calculation under the condition of meeting the calculation requirement;

[0065] The CFD simulation is performed on the demister in the typical working condition desulfurization system to obtain detailed flow field information, and the flow field velocity, pressure drop and outlet droplet content information obtained by experiment are compared and verified, so that the calculation model meets the engineering error requirement;

[0066] CFD numerical simulation is performed on the demister in the desulfurization system under different load, inlet delay flow, liquid-gas ratio, temperature and pressure operating conditions, a flow field uniformity index is introduced to quantitatively represent the uniformity of the flow field under different operating conditions, the corresponding relationship between different control parameters and the key indicators of the outlet droplet content and resistance performance of the demister is analyzed, and the optimization matching principle between the performance of the demister in the desulfurization system and the operating parameters is determined;

[0067] The qualitative and quantitative effects of the blade spacing, blade type and channel number of the demister in the desulfurization system on the flow field distribution, resistance characteristics and droplet motion are studied, CFD numerical simulation is performed on the demister with different structural designs in the typical working condition desulfurization system, the influence of the mechanism design on the flow field performance is analyzed, the blocking structure area of the droplet aggregation induced air is proposed, and the improved design scheme is repeated for CFD simulation using the optimized design parameters to verify the performance improvement.

[0068] This embodiment is only an exemplary description of the present application and does not limit the protection scope thereof, and a person skilled in the art can also make changes to it, as long as the spirit and essence of the present application are not exceeded, and it is within the protection scope of the present application.

Claims

1. A control system for solving 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 connected to the gypsum dehydration system (3), the pulping system (4) and the absorption tower through multiple pipes. The industrial water tank (2) is connected to the gypsum dehydration system (3) and the wastewater system (5) through pipes. The gypsum dehydration system (3) and the pulping system (4) are connected to the absorption tower through pipes. The absorption tower comprises a The primary absorption tower (7) and the secondary absorption tower (8) are connected via 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) via a pipeline. The primary 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. 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. The system is capable of performing the following methods: Step 1: Analyze 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; 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 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 calculate the effective parameters in a 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 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; Step 4: The desulfurization system water balance multi-mechanism operation is carried out. According to the actual operation logistics information of the desulfurization system, the desulfurization system water balance system is established. Combined 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, the desulfurization water balance multi-mechanism operation mode under typical working conditions is established. The demister 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).

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 sequentially arranged in the primary absorption tower (7) from bottom to top. 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) includes 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 machined 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 mist eliminator 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 control method, which is based on the desulfurization mist eliminator blockage and scaling 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), analysis of the properties of the scaling substances, and inspection of the flushing water system; 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 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 calculate the effective parameters in a 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 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; Step 4: The desulfurization system water balance multi-mechanism operation is carried out. According to the actual operation logistics information of the desulfurization system, the desulfurization system water balance system is established. Combined 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, the desulfurization water balance multi-mechanism operation mode under typical working conditions is established. The demister 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).

6. A method for controlling blockage and scaling of a desulfurization mist eliminator according to claim 5, characterized in that: The step 1 is specifically as follows: the flue gas flow rate adaptability test is to test the flue gas flow rate, droplets, coordinated dust removal efficiency and desulfurization tower demister resistance at the demister (12) inlet and the first-stage absorption tower (7) outlet when the unit is in hot operation, and analyze 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 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 fouling properties of the demister (12); Flushing water system inspection refers to the process of 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 (12) is blocked, conducting cold tests on the flushing water system, and analyzing the operating status of the flushing water system.

7. A method for controlling blockage and scaling of a desulfurization mist eliminator 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 SO2 concentration, flue gas component volume fraction, ambient temperature, atmospheric pressure, and limestone purity. The control targets include overall desulfurization efficiency, calcium-sulfur ratio, oxygen-sulfur ratio, average specific heat capacity of each stream component, reaction enthalpy change, and the relative error requirements for thermal balance required by the project. Calculate the logistics components of the inlet flue gas, oxidation air, and outlet flue gas, and determine the process volume of the desulfurization system based on the moisture 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 heat input of the desulfurization system, including the total enthalpy of the inlet flue gas, the total enthalpy of the oxidizing air, the enthalpy of the limestone, the heat of reaction, and the enthalpy of the process water; calculate the heat output 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. The method for controlling blockage and scaling of a desulfurization mist eliminator according to claim 5, characterized in that: The step three is specifically as follows: A Euler-Lagrangian numerical simulation method for multiphase flow in a desulfurization system demister under typical operating conditions was established. The flue gas flowing in the demister was considered a continuous phase, and its continuity equation, momentum equation, and energy equation were constructed to solve the flue gas flow. The droplets carried in the flue gas were considered as single spherical droplets, which were tracked separately using the Lagrangian method. The balance equation of the forces acting on the droplet particles was constructed to solve their motion trajectory and velocity. The desulfurization system demister was processed using a porous medium model to reduce the difficulty of meshing and the amount of mesh calculation while meeting the calculation requirements. CFD simulation was performed on the mist eliminator of a typical desulfurization system to obtain detailed flow field information. This information was then compared with experimentally measured flow field velocity, pressure drop, and outlet droplet content to ensure that the calculation model met engineering error requirements. Conduct CFD numerical simulations of the desulfurization system demister under different load, inlet delayed flow, liquid-to-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. Determine the optimal 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 working conditions are carried out. The influence of their structural design on the flow field performance and the blockage structure area where droplets gather and bleed air are analyzed. Improved design schemes are proposed, and CFD simulations are repeated using the optimized design parameters to verify the performance improvement.

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