Method of calculating effect of jointly removing particulate substance in wet-type exhaust-gas desulfurization device of serial tower type

Abstract

To provide a method of calculating the effect of jointly removing particulate substances in a wet-type exhaust-gas desulfurization device of a serial tower type, relating to a technology field of wet-type exhaust-gas desulfurization.SOLUTION: A whole-part-whole method is employed to simulate and perform calculation in relation to a flue system, a demister, a pre-washing tower, and an absorption tower stepwise respectively. Specifically, the whole simulation of a monophase flow is employed to quickly obtain the flow velocity distribution and the temperature distribution of the inlet cross-sections of the pre-washing tower and the absorption tower, to obtain the collection efficiency curves of the pre-washing tower demister and the absorption tower demister for dust particles of different particle sizes and droplet slurry by carrying out calculation using a demister sub-model. Based on the two steps, the joint removal of the three-phase flow flowing in the tower is simulated and calculations are performed in relation to the pre-washing tower and the absorption tower, to quickly and quantitatively calculate the effect of jointly removing the particulate matter in the wet-type exhaust-gas desulfurization device of a serial two-stage tower type.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the technical field of wet flue gas desulfurization, and particularly to a method for calculating the particulate matter co-removal effect of a series tower type wet flue gas desulfurization device.

Background Art

[0002] Wet flue gas desulfurization is a widely used desulfurization method at present, which is used at the end before the flue gas enters the chimney. As environmental standards are becoming increasingly stringent, the conventional single tower desulfurization device can no longer meet the needs. When the efficiency of single tower desulfurization cannot meet the emission requirements, a configuration in which a pre-washing tower and an absorption tower are connected in series in two stages becomes an effective desulfurization means.

[0003] The dust components in the flue gas after wet desulfurization can be divided into two parts. One part is the dust particles that have not been washed away from the flue gas, and the other part is the slurry droplets carried by the flue gas. The dust particles are collected at a certain ratio by both the spray area and the demister in the pre-washing tower and the absorption tower, but the removal of the slurry droplets mainly occurs in the demister. The removal theories of dust particles and slurry droplets are different, the process is complicated, and there is no established theory and empirical formula for reference.

[0004] Computational Fluid Dynamics (CFD) can simulate and calculate the flue gas flow and gas-liquid-solid three-phase flow in the desulfurization tower as a tool for design optimization. However, the structure and removal theory in the tower are very complicated, the removal theory varies by region, and the removal situations in different regions affect each other, so the removal effect of the desulfurization system cannot be directly calculated. Therefore, an effective calculation of the particulate matter co-removal by numerical fluid dynamics for a series tower type desulfurization system has become a technical problem that needs to be solved urgently.

Summary of the Invention

Problems to be Solved by the Invention

[0005] An embodiment of the present invention provides a method for calculating the particulate matter co-removal effect of a series-type tower wet flue gas desulfurization device for the above problems.

Means for Solving the Problems

[0006] An embodiment of the present invention is Step S1 of establishing an overall model of a series two-stage tower flue gas system and collecting operating state parameters of the series two-stage tower flue gas system; Step S2 of performing a simulation and calculation of the single-phase flow of the series two-stage tower flue gas system using the established overall model to obtain the flow field distribution of the series two-stage tower flue gas system; Step S3 of cutting out the inlet cross-sections of the preliminary washing tower and the absorption tower, and respectively obtaining the gas velocity distribution, temperature distribution, and dust particle size distribution at each inlet cross-section based on the obtained flow field distribution; Step S4 of establishing a demister model in the preliminary washing tower, performing a detailed simulation and calculation of the gas-solid-liquid three-phase flow, and obtaining the collection efficiency curves for dust particles and slurry droplets of different particle sizes by the demister in the preliminary washing tower; Using the gas velocity distribution, temperature distribution, and dust particle size distribution of the exhaust gas at the inlet cross-section of the preliminary washing tower as boundary conditions, and using the collection efficiency curves for dust particles and slurry droplets of different particle sizes by the demister in the preliminary washing tower as input conditions, performing a simulation and calculation of the gas-liquid-solid three-phase flow for the preliminary washing tower to obtain the amounts of dust particles and slurry droplets of different particle sizes flowing out from the outlet of the preliminary washing tower in Step S5; Step S6 of establishing a demister model in the absorption tower, performing a detailed simulation and calculation of the gas-solid-liquid three-phase flow, and obtaining the collection efficiency curves for dust particles and slurry droplets of different particle sizes by the demister in the absorption tower; Taking the flow velocity distribution, temperature distribution, dust particle size distribution of the exhaust gas at the inlet cross-section of the absorption tower, and the amounts of dust particles and slurry droplets with different particle sizes flowing out from the outlet of the preliminary scrubber as boundary conditions, and taking the collection efficiency curves of the dust particles and slurry droplets with different particle sizes of the demister in the absorption tower as input conditions, performing gas-liquid-solid three-phase flow simulation and calculation on the absorption tower to obtain the amounts of dust particles and slurry droplets with different particle sizes flowing out from the outlet of the absorption tower, step S7; Step S8 of determining the co-removal effect by calculating the sum of the amounts of dust particles with different particle sizes flowing out from the outlet of the absorption tower and the solids content of the slurry droplets, and providing a method for calculating the particulate matter co-removal effect of a series-type tower wet flue gas desulfurization device.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows. Adopting the overall-partial-overall method, performing step-by-step simulation and calculation on the flue gas system, demister, preliminary scrubber and absorption tower respectively. Specifically, adopting the overall simulation of single-phase flow to quickly obtain the flow velocity distribution and temperature distribution of the inlet cross-section of the preliminary scrubber and the absorption tower, and adopting the demister sub-model to calculate to obtain the collection efficiency curves of the dust particles and droplet slurries with different particle sizes of the preliminary scrubber demister and the absorption tower demister. Based on these two steps, performing the simulation and calculation of the co-removal of the three-phase flow flowing in the tower for the preliminary scrubber and the absorption tower, the particulate matter co-removal effect of the series two-stage tower wet flue gas desulfurization device can be calculated quickly and quantitatively. Compared with the normal overall simulation and calculation method, the present invention enables the numerical calculation of particulate matter co-removal and obtains accurate calculation results.

[0008] Optionally, in step S1, the operating state parameters of the system include the inlet exhaust gas volume, inlet exhaust gas temperature, diameter of the preliminary scrubber, height of the preliminary scrubber, number of spray layers of the preliminary scrubber, dust concentration at the inlet of the preliminary scrubber, diameter of the absorption tower, height of the absorption tower, and number of spray layers of the absorption tower.

[0009] Optionally, in step S2, in the process of simulating and calculating the single-phase flow of the two-stage chimney flue system in series, a turbulent flow model and a mass transfer model are selected to simulate and calculate the flue gas flow in the flue, and the Lagrangian discrete phase model is adopted to simulate and calculate the dust particles. The calculation area is from the outlet of the fan to the inlet of the chimney, including the connecting flue, the preliminary scrubber body, and the absorber body.

[0010] Optionally, in step S4, in the process of simulating and calculating the detailed gas-solid-liquid three-phase flow, the formula by Slinn is used for the removal of dust particles, comprehensively considering the interaction of the gas-liquid-solid three phases, and the removal efficiency of the demister in the preliminary scrubber for dust particles with different particle sizes is calculated. The water-film model is used to calculate the removal efficiency of the slurry droplets.

[0011] Optionally, the formula by Slinn is E(D d ,d p )=E di (D d ,d p )+E it (D d ,d p )+E im (D d ,d p ) where in the formula, E di (D d ,d p ), E it (D d ,d p ), E im (D d ,d p ) are the contributions to the collection efficiency E(D d ,d p ) of the diffusion, interception, and inertial mechanisms respectively, and their calculation formulas are respectively E di (D d ,d p )=4 / ReSc[1+0.4Re 1 / 2 Sc 1 / 3 +0.16Re 1 / 2 Sc1 / 2 E it (D d ,d p ) = 4φ[ω -1 +(1 + 2Re 1 / 2 )φ] E im (D d ,d p ) = [(St - St * ) / (St - St * + 0.667)] 3 / 2 (ρ p / ρ w ) 1 / 2 where In the formula Re = D d U t (D d )ρ a / 2μ a Sc = μ a / ρ a D St = 2U t (D d )τ a / D d φ = d p / D d ω = μ w / μ a St * =(1.2+(1 / 12ln(1 + Re))) / (1 + ln(1 + Re)) U t (D d ) = aD d b (ρ a0 / ρ a ) 0.4 Re is the Reynolds number, Sc is the Schmidt number of the fly ash particles, St is the Stokes number of the fly ash particles, St * is the critical Stokes number, U t (D d ​) is the final falling velocity of the slurry. In the formula, a and b are constants, where a = 842 and b = 0.8. φ is the particle size ratio of fly ash particles to slurry droplets, ω is the viscosity ratio of the slurry to the exhaust gas. d p is the particle size of fly ash particles, and D d is the particle size of the slurry, D is the diffusion coefficient of fly ash particles, μ w is the viscosity of the slurry, and μ a is the viscosity of the exhaust gas. ρ p is the particle density of fly ash, and ρ w is the density of the slurry, and ρ a is the density of the exhaust gas, and ρ a0 is the density of the standard exhaust gas, τ a is the relaxation time of the particles, and D d b is the b-th power of the particle size of the slurry.

[0012] Optionally, in step S5, in the process of simulating and calculating the gas-liquid-solid three-phase flow for the pre-washing tower, a porous medium model is adopted in the demister region. The particle size distribution of the slurry at the outlet of the nozzles in the spray layer is set according to the designed particle size distribution of the nozzles. Regarding the removal efficiency of dust particles in the spray layer region, the formula by Slinn is used to comprehensively consider the interaction of the gas-liquid-solid three phases, and the removal efficiency of dust particles with different particle sizes in the spray layer region is calculated. The removal efficiency of slurry droplets is calculated using the Water-Film model.

[0013] Optionally, the inlet exhaust gas volume includes the sum of the exhaust gas volumes at the outlets of each fan. For an inoperative series tower type exhaust gas wet desulfurization device, the inlet exhaust gas temperature may be obtained based on the design parameters and test data of similar projects. For an operating series tower type exhaust gas wet desulfurization device, the inlet exhaust gas temperature may be obtained based on the on-site monitoring data.

[0014] Optionally, for an inoperative series tower type wet flue gas desulfurization device, calculate based on 15% solids content, and for an operating series tower type wet flue gas desulfurization device, actually measure and obtain on-site production data.

Brief Description of the Drawings

[0015] The drawings described herein are for a further understanding of the invention as a part of this application and do not constitute a limitation to the invention.

[0016]

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Embodiments for Carrying out the Invention

[0017] Hereinafter, the present invention will be described in more detail with reference to embodiments and drawings so that the objects, technical solutions and advantages of the present invention will become clearer. Here, the exemplary embodiments of the present invention and their descriptions are for interpreting the present invention and do not limit the present invention.

[0018] Referring to FIG. 1, the embodiment of the present invention provides a calculation method for the co-removal effect of particulate matter of a series tower type exhaust gas wet desulfurization device, including the following. Step S1, establishing an overall model of the series two-stage tower type flue system and collecting the operating state parameters of the series two-stage tower type flue system.

[0019] In implementation, the series two-stage tower type exhaust gas wet desulfurization device shown in FIG. 2 includes a preliminary washing tower 2 and an absorption tower 4 provided in series. The series two-stage tower type flue system includes an inlet flue 1 of the preliminary washing tower, a connecting flue 3 between the preliminary washing tower 2 and the absorption tower 4, and an outlet flue 5 of the absorption tower. The operating state parameters of the system include the inlet exhaust gas volume, the inlet exhaust gas temperature, the diameter of the preliminary washing tower, the height of the preliminary washing tower, the number of spray layers of the preliminary washing tower, the dust concentration at the inlet of the preliminary washing tower, the diameter of the absorption tower, the height of the absorption tower, and the number of spray layers of the absorption tower.

[0020] However, the inlet exhaust gas volume includes the total exhaust gas volume at the outlet of each fan. For an inoperative two-stage series wet flue gas desulfurization device, the inlet exhaust gas temperature may be obtained based on the design parameters and test data of similar projects. A similar project refers to a project with the same or similar production scale. For an operating two-stage series wet flue gas desulfurization device, the inlet exhaust gas temperature may be obtained based on on-site monitoring data.

[0021] Step S2: Using the established overall model, perform a simulation and calculation of the single-phase flow in the two-stage series flue gas system to obtain the flow field distribution of the two-stage series flue gas system.

[0022] In implementation, in the process of simulating and calculating the single-phase flow of the two-stage series flue gas system, select a turbulent flow model and a mass transport model to simulate and calculate the exhaust gas flow in the flue, and adopt a Lagrangian discrete phase model to simulate and calculate the dust particles. The calculation area is from the outlet of the fan to the inlet of the chimney, including the connecting flue, the main body of the preliminary scrubber, the main body of the absorption tower, etc.

[0023] Step S3: Cut out the inlet cross-sections of the preliminary scrubber and the absorption tower, and based on the obtained flow field distribution, respectively obtain the exhaust gas velocity distribution, temperature distribution, and dust particle size distribution at each inlet cross-section.

[0024] In implementation, the position of the cut inlet cross-section is generally the position between the downstream of the last elbow of the inlet flue and the preliminary scrubber (absorption tower).

[0025] Step S4: Establish a demister model in the preliminary scrubber, perform a detailed simulation and calculation of the gas-solid-liquid three-phase flow, and obtain the collection efficiency curves for dust particles and slurry droplets of different particle sizes in the demister in the preliminary scrubber.

[0026] In the implementation process of detailed simulation and calculation of gas-solid-liquid three-phase flow, a model is created according to the actual structure of the demister in the preliminary washing tower. When performing simulation and calculation, the demister in the preliminary washing tower can be grid-divided, and the entire demister can be divided into multiple calculation units. By calculating the data in each calculation unit, the overall distribution situation of the entire demister can be obtained. Theoretically, the finer the grid is divided, the better. However, if the grid is too fine, the calculation amount will be very large, and the calculation resources cannot handle it. Generally, when the grid is fine enough, the actual state can be fully reflected, and the specific size of the grid may be determined by grid independence verification.

[0027] Specifically, in the process of simulation and calculation, regarding the removal of dust particles, the formula by Slinn is used to comprehensively consider the interaction of gas-liquid-solid three phases, and the removal efficiency of dust particles with different particle sizes by the demister in the preliminary washing tower is calculated. The removal efficiency of slurry droplets is calculated using the Water-Film model. Specifically, the improved formula by Slinn is E(D d ,d p )=E di (D d ,d p )+E it (D d ,d p )+E im (D d ,d p ) That is, In the formula, E di (D d ,d p ), E it (D d ,d p ), E im (D d ,d p ) are the contributions to the collection efficiency E(D d ,d p ) of the diffusion, blocking, and inertial mechanisms respectively, and their calculation formulas are respectively E di (D d,d p ) = 4 / ReSc[1 + 0.4Re 1 / 2 Sc 1 / 3 + 0.16Re 1 / 2 Sc 1 / 2 E it (D d ,d p ) = 4φ[ω -1 +(1 + 2Re 1 / 2 )φ] E im (D d ,d p ) = [(St - St * ) / (St - St * + 0.667)] 3 / 2 (ρ p / ρ w ) 1 / 2 where In the formula Re = D d U t (D d )ρ a / 2μ a Sc = μ a / ρ a D St = 2U t (D d )τ a / D d φ = d p / D d ω = μ w / μ a St * =(1.2+(1 / 12ln(1 + Re))) / (1 + ln(1 + Re)) U t (D d ) = aD d b (ρ a0 / ρ a ) 0.4 Re is the Reynolds number, Sc is the Schmidt number of the fly ash particles, St is the Stokes number of the fly ash particles, St * is the critical Stokes number, U t (D​d ) is the final falling velocity of the slurry, where a and b are constants, a = 842, b = 0.8, φ is the particle size ratio of fly ash particles to slurry droplets, ω is the viscosity ratio of the slurry to the exhaust gas, d p is the particle size of the fly ash particles, D d is the particle size of the slurry, D is the diffusion coefficient of the fly ash particles, μ w is the viscosity of the slurry, μ a is the viscosity of the exhaust gas, ρ p is the particle density of the fly ash, ρ w is the density of the slurry, ρ a is the density of the exhaust gas, ρ a0 is the density of the standard exhaust gas, τ a is the relaxation time of the particles, D d b is the b-th power of the particle size of the slurry.

[0028] The water-film model is a mathematical model incorporated in CFD software. By this model, the situation where discrete droplets form a continuous liquid film can be calculated, and furthermore, the droplets that flow out without forming a liquid film can be calculated.

[0029] In step S5, taking the flow velocity distribution, temperature distribution, and dust particle size distribution of the exhaust gas at the inlet cross-section of the preliminary scrubber as boundary conditions, and taking the collection efficiency curves for dust particles and slurry droplets of different particle sizes in the demister in the preliminary scrubber as input conditions, perform the simulation and calculation of the gas-liquid-solid three-phase flow for the preliminary scrubber to obtain the amounts of dust particles and slurry droplets of different particle sizes flowing out from the outlet of the preliminary scrubber.

[0030] In implementation, when performing CFD calculations on the overall co-removal effect of the preliminary scrubbing tower, a porous media model is adopted for the demister region. The particle size distribution of the slurry at the outlet of the nozzles in the spray layer can be set according to the designed particle size distribution of the nozzles, or it can also be set according to the particle size distribution provided by the nozzle manufacturer. Regarding the removal efficiency of dust particles in the spray layer region, the equation by Slinn is used to comprehensively consider the interaction of the gas-liquid-solid three phases, and the removal efficiency of dust particles with different particle sizes in the spray layer region is calculated. The removal efficiency of slurry droplets is calculated using the Water-Film model. Also, the collection efficiency of the demister for dust particles and slurry droplets with different particle sizes is obtained by performing an overall calculation on the preliminary scrubbing tower in a method with the preliminary scrubbing tower demister efficiency model as a sub-model, so as to obtain the amounts of dust particles and slurry droplets with different particle sizes flowing out from the outlet of the preliminary scrubbing tower.

[0031] Step S6, establishing a demister model inside the absorption tower, performing detailed simulations and calculations of the gas-solid-liquid three-phase flow, and obtaining the collection efficiency curves of the demister inside the absorption tower for dust particles and slurry droplets with different particle sizes.

[0032] Step S7, taking the gas velocity distribution, temperature distribution, dust particle size distribution at the inlet cross-section of the absorption tower, and the amounts of dust particles and slurry droplets with different particle sizes flowing out from the outlet of the preliminary scrubbing tower as boundary conditions, and taking the collection efficiency curves of the demister inside the absorption tower for dust particles and slurry droplets with different particle sizes as input conditions, performing simulations and calculations of the gas-liquid-solid three-phase flow for the absorption tower, and obtaining the amounts of dust particles and slurry droplets with different particle sizes flowing out from the outlet of the absorption tower.

[0033] In implementation, since the process of the detailed simulations and calculations of the gas-solid-liquid three-phase flow by the demister model inside the absorption tower and the simulations and calculations of the gas-liquid-solid three-phase flow for the entire absorption tower is the same as the principle of the preliminary scrubbing tower, it will not be elaborated here in detail.

[0034] In step S8, the co-removal effect is determined by calculating the sum of the amounts of dust particles with different particle diameters flowing out from the outlet of the absorption tower and the solid content of the slurry droplets.

[0035] In implementation, for an unoperated series tower type flue gas wet desulfurization device, it is calculated based on a solid content of 15%, and for an operating series tower type flue gas wet desulfurization device, on-site production data is actually measured and obtained.

[0036] (Example) In step 1, an overall model of the series two-stage tower type flue duct system is established, and its operating state parameters are collected. Here, as shown in Figure 3, for the three-dimensional model of the series two-stage tower type flue duct system, two fans are provided in the inlet flue of the preliminary washing tower, and the operating state parameters are as shown in Table 1.

Table 1

[0037] In step 2, a simulation and calculation of the single-phase flow of the series two-stage absorption tower flue duct system are performed to obtain the flow field distribution of the series two-stage absorption tower flue duct system.

[0038] In step 3, the inlet cross-sections of the preliminary washing tower and the absorption tower are cut out to obtain the exhaust gas velocity distribution, temperature distribution, and dust particle size distribution respectively. Here, the exhaust gas velocity distribution at the inlet cross-section of the preliminary washing tower is shown in Figure 4, and the exhaust gas velocity distribution at the inlet cross-section of the absorption tower is shown in Figure 5.

[0039] Step 4: Establish the demister model inside the preliminary washing tower, conduct detailed simulations and calculations of the gas-solid-liquid three-phase flow, and obtain the collection efficiency curves for dust particles and slurry droplets with different particle sizes in the demister inside the preliminary washing tower. The demister model inside the preliminary washing tower in the process of simulation and calculation is shown in Figure 6, and the grid division is shown in Figure 7. The collection efficiency curves for dust particles with different particle sizes in the demister inside the preliminary washing tower are shown in Figure 8, where the collection efficiency curves for dust particles with different particle sizes at three velocities of 3.5 m / s, 4.0 m / s, and 4.5 m / s are shown. The slurry droplet collection efficiency curve is shown in Figure 9, where the collection efficiency curves for slurry droplets with different particle sizes at three velocities of 3.5 m / s, 4.0 m / s, and 4.5 m / s are shown.

[0040] Step 5: Conduct simulations and calculations of the gas-liquid-solid three-phase flow for the preliminary washing tower to obtain the amounts of dust particles and slurry droplets with different particle sizes flowing out from the outlet of the preliminary washing tower. The trajectories of the dust particles inside the preliminary washing tower in the simulation and calculation are shown in Figure 10, and the trajectories of the slurry droplets are shown in Figure 11.

[0041] Step 6: Conduct detailed simulations of the gas-solid-liquid three-phase flow of the sub-model for the demister inside the absorption tower to obtain the collection efficiency curves for dust and slurry droplets with different particle sizes. The dust particle collection efficiency curve of the demister inside the absorption tower in the simulation and calculation is shown in Figure 12, where the collection efficiency curves for dust particles with different particle sizes at three velocities of 3.5 m / s, 4.0 m / s, and 4.5 m / s are shown. The slurry droplet collection efficiency curve is shown in Figure 13, where the collection efficiency curves for slurry droplets with different particle sizes at three velocities of 3.5 m / s, 4.0 m / s, and 4.5 m / s are shown.

[0042] Step 7: Perform simulation and calculation on the gas-liquid-solid three-phase flow in the absorption tower to obtain the amounts of dust particles and slurry droplets with different particle sizes flowing out from the outlet of the absorption tower. The trajectories of the dust particles in the absorption tower in the simulation and calculation are shown in Fig. 14, and the trajectories of the slurry droplets in the absorption tower are shown in Fig. 15.

[0043] Step 8: Add the solid content of a predetermined proportion of the slurry droplets at the outlet of the absorption tower and the amount of dust particles at the outlet of the absorption tower to obtain the discharge concentration of the solid particulate matter at the outlet of the two-stage series absorption tower.

[0044] After simulation and calculation, statistically analyze the particulate matter concentration distribution at different positions of the two-stage series wet flue gas desulfurization device to obtain the distribution diagram shown in Fig. 16. As a result of the calculation, the dust concentration at the outlet of the absorption tower is 2.8 mg / Nm 3 and the slurry droplet concentration is 12.2 mg / Nm 3 Calculating with 15% solid content of the circulating slurry, the solid concentration at the outlet of the absorption tower is 1.83 mg / Nm due to the transportation of the slurry 3 and the total discharge concentration obtained by adding the two is 4.63 mg / Nm 3 which meets the discharge standard.

[0045] The solution provided by the present invention adopts the overall-partial-overall method to perform simulation and calculation on the flue gas system, demister, pre-washing tower and absorption tower step by step. Specifically, by adopting the overall simulation of single-phase flow, the flow velocity distribution and temperature distribution of the inlet cross-section of the pre-washing tower and the absorption tower can be quickly obtained, and by adopting the demister sub-model for calculation, the collection efficiency curves for dust particles and droplet slurries with different particle sizes of the pre-washing tower demister and the absorption tower demister can be obtained. Based on these two steps, when performing simulation and calculation on the co-removal of the three-phase flow flowing in the pre-washing tower and the absorption tower, the co-removal effect of particulate matter of the two-stage series wet flue gas desulfurization device can be calculated quickly and quantitatively. Compared with the normal overall simulation and calculation method, the present invention enables the numerical calculation of the co-removal of particulate matter and obtains accurate calculation results.

[0046] The above are not limitations to the protection scope of the present invention, but merely preferred embodiments of the present invention. Any changes, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention shall be included in the protection scope of the present invention.

Description of Reference Numerals

[0047] 1 Inlet flue of the preliminary scrubbing tower 2 Preliminary scrubbing tower 3 Connecting flue 4 Absorption tower 5 Outlet flue of the absorption tower SP1 Spray layer inside the preliminary scrubbing tower ME1 Demister inside the preliminary scrubbing tower SP2 Spray layer inside the absorption tower ME2 Demister inside the absorption tower

Claims

1. Step S1: establishing a whole model of a series two-stage tower flue system and collecting operating state parameters of the series two-stage tower flue system; S2: simulating and calculating the single-phase flow of the series two-stage tower flue system using the established overall model to obtain the flow field distribution of the series two-stage tower flue system; Step S3 of cutting out the inlet cross sections of the preliminary scrubber and the absorption tower, and acquiring the flow velocity distribution, temperature distribution, and dust particle size distribution of the exhaust gas at each inlet cross section based on the obtained flow field distribution; Step S4: Establish a demister model in the pre-washing tower, and perform detailed gas-solid-liquid three-phase flow simulation and calculation to obtain collection efficiency curves for dust particles and slurry droplets of different particle sizes of the demister in the pre-washing tower; Step S5: simulating and calculating a gas-liquid-solid three-phase flow in the pre-scrubbing tower using the flow velocity distribution, temperature distribution and dust particle size distribution of the exhaust gas at the inlet cross section of the pre-scrubbing tower as boundary conditions and the collection efficiency curve for dust particles and slurry droplets of different particle sizes of the demister in the pre-scrubbing tower as input conditions, to obtain the amounts of dust particles and slurry droplets of different particle sizes flowing out from the outlet of the pre-scrubbing tower; Step S6: Establish a demister model in the absorption tower, and perform detailed simulation and calculation of gas-solid-liquid three-phase flow to obtain collection efficiency curves for dust particles and slurry droplets of different particle sizes of the demister in the absorption tower; Step S7 of simulating and calculating a gas-liquid-solid three-phase flow in the absorption tower using the flow velocity distribution, temperature distribution, and dust particle size distribution of the exhaust gas at the inlet cross section of the absorption tower, and the amount of dust particles and slurry droplets with different particle sizes flowing out from the outlet of the preliminary scrubbing tower as boundary conditions, and using the collection efficiency curve for dust particles and slurry droplets with different particle sizes of the demister in the absorption tower as input conditions, to obtain the amount of dust particles and slurry droplets with different particle sizes flowing out from the outlet of the absorption tower; A method for calculating the joint particulate matter removal effect of a series tower type flue gas wet method desulfurization apparatus, comprising: a step S8 of determining the joint removal effect by calculating the sum of the amount of dust particles with different particle diameters flowing out from the outlet of the absorption tower and the solid content of the slurry droplets.

2. The method for calculating the joint particulate matter removal effect of a series tower type flue gas wet process desulfurization apparatus as described in claim 1, characterized in that in step S1, the system operating state parameters include: inlet flue gas volume, inlet flue gas temperature, diameter of the pre-scrubbing tower, height of the pre-scrubbing tower, number of spray layers of the pre-scrubbing tower, dust concentration at the inlet of the pre-scrubbing tower, diameter of the absorption tower, height of the absorption tower, and number of spray layers of the absorption tower.

3. The method for calculating the joint particulate matter removal effect of a series-type flue gas wet desulfurization apparatus as described in claim 1, characterized in that in step S2, in the process of simulating and calculating the single-phase flow of a series-type two-tower flue system, a turbulence model and a mass transport model are selected to simulate and calculate the flue gas flow, and a Lagrangian discrete phase model is adopted to simulate and calculate the dust particles, the calculation area is from the fan outlet to the chimney inlet, and includes the connecting flue, the pre-scrubber body and the absorber body.

4. The method for calculating the joint particulate matter removal effect of a series tower type flue gas wet process desulfurization apparatus according to claim 1, characterized in that in step S4, in the process of performing detailed gas-solid-liquid three-phase flow simulation and calculation, the Slinn formula is used to comprehensively consider the gas-liquid-solid three-phase interaction for dust particle removal, the removal efficiency of dust particles with different particle sizes in the demister in the preliminary scrubbing tower is calculated, and the removal efficiency of slurry droplets is calculated using a water film model.

5. The formula by Slinn is: E(D ｄ ,d ｐ )=E ｄｉ (D ｄ ,d ｐ )+E ｉｔ (D ｄ ,d ｐ )+E ｉｍ (D ｄ ,d ｐ ) and In the formula, E ｄｉ (D ｄ , d ｐ ), E ｉｔ (D ｄ , d ｐ ), E ｉｍ (D ｄ , d ｐ ) are the collection efficiencies E(D ｄ , d ｐ ) and the formulas for calculating them are: E ｄｉ (D ｄ ,d ｐ )\4 / Reｳc[+00.42e １／２ ｳc １／３ 00.162e １／２ ｳc １／２ ) E ｉｔ (D) ｄ ,d ｐ )=4φ[ω －１ + (1 + 2 Re) １／２ )φ] E ｉｍ (D ｄ ,d ｐ )=[(St-St ＊ ) / (St-St ＊ +0.667)] ３／２ (ρ ｐ / ρ ｗ ) １／２ and During the ceremony, DR ｄ 10 ｔ (5) ｄ )ρ ａ 22μ ａ Sc=μ ａ / r ａ D 2020 ｔ (5) ｄ )τ ａ 30 ｄ φ=d ｐ / D ｄ ω=μ ｗ / m ａ St ＊ =(1.2+(1 / 12ln(1+Re))) / (1+ln(1+Re)) U ｔ (D) ｄ )=aD ｄ ｂ (p) ａ０ / r ａ ) ０．４ Re is the Reynolds number, Sc is the Schmidt number of the fly ash particles, St is the Stokes number of the fly ash particles, and St ＊ is the critical Stokes number, U ｔ (D ｄ ) is the final falling velocity of the slurry, where a and b are constants, a = 842 and b = 0.8, φ is the particle size ratio of the fly ash particles to the slurry droplets, and ω is the viscosity ratio of the slurry to the exhaust gas. d ｐ is the particle diameter of the fly ash particles, and D ｄ is the particle size of the slurry, D is the diffusion coefficient of the fly ash particles, and μ ｗ is the viscosity of the slurry, and μ ａ is the viscosity of the exhaust gas, ρ ｐ is the particle density of fly ash, and ρ ｗ is the density of the slurry, and ρ ａ is the density of the exhaust gas, and ρ ａ０ is the density of the standard exhaust gas, and τ ａ is the relaxation time of the particle, D ｄ ｂ The method for calculating the joint particulate matter removal effect of a series tower type flue gas wet desulfurization apparatus according to claim 4, wherein is the b power of the particle diameter of the slurry.

6. In step S5, in the process of simulating and calculating the gas-liquid-solid three-phase flow for the pre-scrubbing tower, a porous medium model is adopted in the demister region, the particle size distribution of the slurry at the outlet of the nozzle of the spray bed is set according to the designed particle size distribution of the nozzle, and the removal efficiency of dust particles in the spray bed region is calculated for dust particles of different particle sizes in the spray bed region by comprehensively considering the interaction between the gas-liquid-solid three-phase using the Slinn formula, and the removal efficiency of slurry droplets is calculated using a water film model.

7. The method for calculating the particulate matter joint removal effect of a series-tower type flue gas wet desulfurization apparatus according to claim 2, characterized in that the inlet flue gas volume includes the sum of the outlet flue gas volumes of each fan, and for an out-of-operation series-tower type flue gas wet desulfurization apparatus, the inlet flue gas temperature can be obtained based on design parameters and test data of similar projects, and for an operation series-tower type flue gas wet desulfurization apparatus, the inlet flue gas temperature can be obtained based on on-site monitoring data.

8. The method for calculating the joint particulate matter removal effect of series-tower type flue gas wet desulfurization devices described in claim 1, characterized in that for an out-of-operation series-tower type flue gas wet desulfurization device, the calculation is performed with a solid content of 15%, and for an operating series-tower type flue gas wet desulfurization device, on-site production data is actually measured and obtained.

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