CN117437987A - Calculation method for cooperative particulate removal effect of tower-type flue gas wet desulfurization device - Google Patents
Calculation method for cooperative particulate removal effect of tower-type flue gas wet desulfurization device Download PDFInfo
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 88
- 239000003546 flue gas Substances 0.000 title claims abstract description 88
- 238000004364 calculation method Methods 0.000 title claims abstract description 75
- 238000006477 desulfuration reaction Methods 0.000 title claims abstract description 43
- 230000023556 desulfurization Effects 0.000 title claims abstract description 43
- 230000000694 effects Effects 0.000 title claims abstract description 24
- 239000002245 particle Substances 0.000 claims abstract description 149
- 239000000428 dust Substances 0.000 claims abstract description 78
- 239000002002 slurry Substances 0.000 claims abstract description 78
- 238000010521 absorption reaction Methods 0.000 claims abstract description 68
- 238000009826 distribution Methods 0.000 claims abstract description 59
- 238000005406 washing Methods 0.000 claims abstract description 58
- 238000004088 simulation Methods 0.000 claims abstract description 57
- 239000007788 liquid Substances 0.000 claims abstract description 56
- 238000000034 method Methods 0.000 claims abstract description 30
- 230000002195 synergetic effect Effects 0.000 claims abstract description 9
- 239000012071 phase Substances 0.000 claims description 41
- 239000007787 solid Substances 0.000 claims description 26
- 239000010881 fly ash Substances 0.000 claims description 18
- 239000006096 absorbing agent Substances 0.000 claims description 15
- 239000007921 spray Substances 0.000 claims description 15
- 230000008569 process Effects 0.000 claims description 13
- 230000007246 mechanism Effects 0.000 claims description 7
- 238000009792 diffusion process Methods 0.000 claims description 6
- 230000003993 interaction Effects 0.000 claims description 6
- 238000012360 testing method Methods 0.000 claims description 6
- 238000013461 design Methods 0.000 claims description 5
- 239000007789 gas Substances 0.000 claims description 5
- 239000007791 liquid phase Substances 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 239000000779 smoke Substances 0.000 claims description 4
- 239000007790 solid phase Substances 0.000 claims description 4
- 238000012544 monitoring process Methods 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 7
- 238000005507 spraying Methods 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000013178 mathematical model Methods 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000005514 two-phase flow Effects 0.000 description 1
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Abstract
The invention relates to the technical field of wet flue gas desulfurization, in particular to a method for calculating the synergistic removal effect of particulate matters of a serial tower type wet flue gas desulfurization device, which adopts an integral-local-integral mode to respectively perform simulation calculation on a flue system, a demister, a pre-washing tower and an absorption tower step by step; the flow velocity distribution and the temperature distribution of inlet sections of the pre-washing tower and the absorption tower are rapidly obtained by adopting single-phase flow integral simulation; acquiring the trapping efficiency curves of the pre-wash tower demister and the absorption tower demister on dust particles and liquid drop slurry with different particle diameters by adopting calculation of a demister submodel; on the basis of the two steps, three-phase flow collaborative removal simulation calculation of the flow in the pre-washing tower and the absorption tower can be performed, and the particle collaborative removal effect of the two-stage serial tower flue gas wet desulphurization device can be rapidly and quantitatively calculated; compared with the conventional integral simulation calculation method, the method can enable the numerical calculation of the cooperative removal of the particulate matters to be possible, and obtain accurate calculation results.
Description
Technical Field
The invention relates to the technical field of wet flue gas desulfurization, in particular to a method for calculating a particle synergistic removal effect of a serial tower type wet flue gas desulfurization device.
Background
The wet desulfurization of the flue gas is a widely applied desulfurization mode at present, and is applied to the extreme end of the flue gas before entering a chimney. With the increasing of environmental protection standards, the existing single-tower desulfurization device cannot meet the requirements, and when the single-tower desulfurization efficiency cannot meet the emission requirements, the two-stage serial arrangement of the pre-washing tower and the absorption tower becomes an effective desulfurization means.
The dust component in the flue gas after wet desulfurization can be divided into two parts, wherein one part is dust particles which are not eluted in the flue gas, and the other part is slurry liquid drops carried by the flue gas; dust particles can be captured in a certain proportion in a spray area and a demister in a pre-washing tower and an absorption tower, and the removal of slurry liquid drops mainly occurs in the demister, so that the dust particles and the slurry liquid drops are different in removal mechanism, the process is complex, and no mature mechanism and an empirical formula can be referred.
The flow field simulation (CFD, computational Fluid Dynamics) is used as a design optimization tool, and can be used for carrying out simulation calculation on the flow of flue gas and the flow of gas, liquid and solid in the desulfurization tower, but the removal effect of the desulfurization system cannot be directly calculated because the structure and the removal mechanism in the tower are very complex, the removal mechanisms in different areas are different and the removal conditions among the different areas are mutually influenced; therefore, how to efficiently perform flow field simulation calculation of the cooperative removal of the particulate matters on the serial tower desulfurization system is a technical problem to be solved.
Disclosure of Invention
Aiming at the problems, the embodiment of the invention provides a method for calculating the cooperative particulate removal effect of a tower-type flue gas wet desulfurization device.
The embodiment of the invention provides a method for calculating the cooperative particulate removal effect of a serial tower type flue gas wet desulfurization device, which comprises the following steps:
s1, establishing a two-stage serial tower flue system integral model and collecting two-stage serial tower flue system operation condition parameters;
s2, performing single-phase flow simulation calculation on the two-stage serial tower flue system by using the established integral model to obtain flow field distribution of the two-stage serial tower flue system;
s3, intercepting inlet sections of the pre-washing tower and the absorption tower, and respectively acquiring flue gas flow velocity distribution, temperature distribution and dust particle size distribution at the inlet sections according to the obtained flow field distribution;
s4, establishing a demister model in the pre-washing tower and performing detailed gas-solid-liquid three-phase flow simulation calculation to obtain a trapping efficiency curve of the demister in the pre-washing tower on dust particles with different particle diameters and slurry liquid drops;
s5, taking flue gas flow velocity distribution, temperature distribution and dust particle size distribution at the inlet section of the pre-washing tower as boundary conditions, taking a collection efficiency curve of a demister in the pre-washing tower for dust particles and slurry liquid drops with different particle sizes as input conditions, and carrying out gas-liquid-solid three-phase flow simulation calculation on the pre-washing tower to obtain the amounts of the dust particles and the slurry liquid drops with different particle sizes, which escape from the outlet of the pre-washing tower;
s6, establishing a demister model in the absorption tower and performing detailed gas-solid-liquid three-phase flow simulation calculation to obtain a trapping efficiency curve of the demister in the absorption tower on dust particles and slurry liquid drops with different particle diameters;
s7, taking the flue gas flow velocity distribution, the temperature distribution, the dust particle size distribution and the amounts of dust particles and slurry droplets in different particle sizes escaping from the outlet of the pre-washing tower at the inlet section of the absorption tower as boundary conditions, taking the trapping efficiency curves of the demister in the absorption tower on the dust particles and the slurry droplets in different particle sizes as input conditions, and carrying out gas-liquid-solid three-phase flow simulation calculation on the absorption tower to obtain the amounts of the dust particles and the slurry droplets in different particle sizes escaping from the outlet of the absorption tower;
s8, calculating the sum of the amounts of dust particles escaping from the outlet of the absorption tower and the solid content of slurry liquid drops under different particle sizes so as to determine the synergistic removal effect.
Compared with the prior art, the invention has the beneficial effects that: adopting an integral-local-integral mode to respectively perform simulation calculation on the flue system, the demister, the pre-washing tower and the absorption tower step by step; the flow velocity distribution and the temperature distribution of inlet sections of the pre-washing tower and the absorption tower are rapidly obtained by adopting single-phase flow integral simulation; acquiring the trapping efficiency curves of the pre-wash tower demister and the absorption tower demister on dust particles and liquid drop slurry with different particle diameters by adopting calculation of a demister submodel; on the basis of the two steps, three-phase flow collaborative removal simulation calculation of the flow in the pre-washing tower and the absorption tower can be performed, and the particle collaborative removal effect of the two-stage serial tower flue gas wet desulphurization device can be rapidly and quantitatively calculated; compared with the conventional integral simulation calculation method, the method can enable the numerical calculation of the cooperative removal of the particulate matters to be possible, and obtain accurate calculation results.
Optionally, the system operation condition parameters in S1 include: inlet flue gas amount, inlet flue gas temperature, pre-scrubber diameter, pre-scrubber height, number of spray layers of pre-scrubber, pre-scrubber inlet dust concentration, absorber diameter, absorber height, and number of spray layers of absorber.
Optionally, in the single-phase flow simulation calculation process of the two-stage serial tower flue system in the step S2, a turbulence model component transportation model is selected to simulate and calculate the flue gas flow of the flue, a Lagrange discrete phase model is adopted to simulate and calculate dust particles, and a calculation domain is from a fan outlet to a chimney inlet and comprises a connecting flue, a pre-wash tower body and an absorption tower body.
Optionally, in the process of performing detailed gas-solid-liquid three-phase flow simulation calculation in S4, the interaction of the gas, liquid and solid phases is comprehensively considered by using a Slin formula to remove dust particles, the removal efficiency of the demister in the pre-washing tower to dust particles with different particle diameters is calculated, and the removal efficiency of slurry liquid drops is calculated by using a Water-Film model.
Alternatively, the Slinn formula is expressed as follows:
in the middle ofAndthe diffusion, interception and inertial mechanisms respectively, are directed to the trapping efficiencyThe calculation formula of the contribution of (a) is as follows:
=
wherein,
is a Reynolds number;schmitt number for fly ash particles;stokes number of fly ash particles;is a critical stokes number;
the final falling speed of the slurry; wherein a is a group of the total number,is a constant, a=842, =0.8；is the particle size ratio of fly ash particles and slurry liquid drops;is the viscosity ratio of slurry and flue gas;
the particle size of the fly ash particles;is the grain size of the slurry;is the diffusion coefficient of fly ash particles;is the viscosity of the slurry;is the viscosity of the flue gas;
is the density of fly ash particles;is slurry density;is the density of the flue gas;is the standard smoke density;is the relaxation time of the particles;is the grain size of the slurryTo the power.
Optionally, in the process of performing gas-liquid-solid three-phase flow simulation calculation on the pre-washing tower in S5, the demister area adopts a porous medium model, the slurry particle size distribution of the spray layer nozzle outlet is set according to the designed particle size distribution of the nozzle, the spray layer area comprehensively considers the interaction of gas-liquid-solid three phases by using a Slinn formula to the dust particle removal efficiency, the removal efficiency of the spray layer area to dust particles with different particle sizes is calculated, and the Water-Film model is used for calculating the slurry liquid drop removal efficiency.
Optionally, the inlet flue gas amount is the sum of outlet flue gas amounts comprising each fan; aiming at the non-operational serial tower type flue gas wet desulfurization device, the inlet flue gas temperature can be obtained according to design parameters and similar project test data; aiming at the series-tower type flue gas wet desulfurization device which is put into operation, the inlet flue gas temperature can be obtained according to on-site monitoring data.
Optionally, aiming at the non-operated tower-type flue gas wet desulfurization device, the solid content is calculated according to 15%; and carrying out actual test acquisition on field production data aiming at the series-tower type flue gas wet desulfurization device which is put into operation.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate and together with the description serve to explain the invention. In the drawings:
FIG. 1 is a schematic flow chart of a method for calculating the cooperative particulate removal effect of a serial tower type flue gas wet desulfurization device;
FIG. 2 is a process flow diagram of a two-stage serial tower type flue gas wet desulfurization device provided by the invention;
FIG. 3 is a schematic diagram of an overall model of a two-stage tower flue system according to the present invention;
FIG. 4 is a graph showing the flow rate distribution of flue gas at the inlet cross section of a pre-wash tower according to the present invention;
FIG. 5 is a graph showing the flow velocity distribution of flue gas at the inlet section of an absorber according to the present invention;
FIG. 6 is a schematic diagram of a demister model in a pre-wash tower provided by the invention;
FIG. 7 is a schematic diagram of mesh division of a demister model in a pre-wash tower provided by the invention;
FIG. 8 is a graph showing the dust particle trapping efficiency of a demister in a pre-wash tower;
FIG. 9 is a graph of the efficiency of mist eliminator slurry droplet collection in a pre-wash tower provided by the present invention;
FIG. 10 is a graph of the dust particle trajectory in a pre-wash tower provided by the invention;
FIG. 11 is a schematic illustration of a trajectory of slurry droplets in a pre-wash tower in accordance with the present invention;
FIG. 12 is a graph showing the dust particle capturing efficiency of a demister in an absorption tower according to the present invention;
FIG. 13 is a graph showing the efficiency of capturing droplets of a demister slurry in an absorber tower according to the present invention;
FIG. 14 is a diagram showing the trajectories of dust particles in an absorber column according to the present invention;
FIG. 15 is a schematic diagram of a trajectory of slurry droplets within an absorber column in accordance with the present invention;
FIG. 16 is a graph showing the concentration distribution of particulate matters at different positions of a two-stage serial tower type wet flue gas desulfurization device provided by the invention.
1, a pre-washing tower inlet flue; 2. a pre-wash tower; 3. connecting the flue; 4. an absorption tower; 5. an outlet flue of the absorption tower;
SP1, spraying a layer in a pre-washing tower; ME1, a demister in the pre-washing tower; SP2, spraying a layer in the absorption tower; ME2, demister in the absorption tower.
Detailed Description
The present invention will be described in further detail with reference to the following embodiments and the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent. The exemplary embodiments of the present invention and the descriptions thereof are used herein to explain the present invention, but are not intended to limit the invention.
Referring to fig. 1, the embodiment of the invention provides a method for calculating a cooperative particulate removal effect of a tower-type flue gas wet desulfurization device, which comprises the following steps:
s1, establishing a two-stage serial tower flue system integral model and collecting two-stage serial tower flue system operation condition parameters.
In practice, referring to fig. 2, the two-stage serial-tower wet flue gas desulfurization device comprises a prewash tower 2 and an absorption tower 4 which are arranged in series, and the two-stage serial-tower flue system comprises a prewash tower inlet flue 1, a connecting flue 3 between the prewash tower 2 and the absorption tower 4 and an absorption tower outlet flue 5;
the system operation condition parameters include: inlet flue gas amount, inlet flue gas temperature, pre-scrubber diameter, pre-scrubber height, number of spray layers of pre-scrubber, pre-scrubber inlet dust concentration, absorber diameter, absorber height, and number of spray layers of absorber.
The inlet flue gas amount is the sum of outlet flue gas amounts of all included fans; aiming at the two-stage serial tower type wet flue gas desulfurization device which is not put into operation, the inlet flue gas temperature can be obtained according to design parameters and test data of similar projects, and the similar projects are projects with the same or close production scale; aiming at the two-stage serial tower type wet flue gas desulfurization device which is put into operation, the inlet flue gas temperature can be obtained according to on-site monitoring data.
S2, performing single-phase flow simulation calculation on the two-stage serial tower flue system by using the established integral model to obtain flow field distribution of the two-stage serial tower flue system.
In the implementation, in the single-phase flow simulation calculation process of the two-stage serial tower flue system, a turbulence model component transportation model is selected to simulate and calculate the flue gas flow of the flue, a Lagrange discrete phase model is adopted to simulate and calculate dust particles, and a calculation area is from a fan outlet to a chimney inlet and comprises a connecting flue, a prewashing tower body, an absorption tower body and the like.
S3, intercepting inlet sections of the pre-washing tower and the absorption tower, and respectively acquiring flue gas flow velocity distribution, temperature distribution and dust particle size distribution at the inlet sections according to the obtained flow field distribution.
In practice, the location of the inlet cross section taken is typically somewhere between the last elbow of the inlet flue downstream to the pre-wash column (absorber).
And S4, establishing a demister model in the pre-washing tower and carrying out detailed gas-solid-liquid three-phase flow simulation calculation to obtain a trapping efficiency curve of the demister in the pre-washing tower on dust particles with different particle diameters and slurry liquid drops.
In the implementation, in the process of carrying out detailed gas-solid-liquid three-phase flow simulation calculation, modeling is carried out according to the actual structure of the demister in the pre-wash tower, during the simulation calculation, the demister in the pre-wash tower can be firstly subjected to grid division, the whole demister is divided into a plurality of calculation units, and the overall distribution condition of the whole demister is obtained by calculating the data in each calculation unit. In theory, the finer the grid division is, the better, but the too fine grid calculation amount is too large, and the calculation resources cannot bear; generally, the grid is finer to a certain degree, so that the actual situation can be completely reflected, and the specific grid size can be determined through grid independence verification.
In one implementation mode, the gas-solid-liquid three-phase flow simulation calculation comprises performing gas-liquid-solid three-phase flow simulation calculation, and comprises, but is not limited to, performing solid-liquid two-phase flow simulation calculation, in the specific simulation calculation process, comprehensively considering the interaction of gas, liquid and solid phases by using a Slin formula to remove dust particles, calculating the removal efficiency of a demister in a pre-washing tower on dust particles with different particle diameters, and calculating the removal efficiency of slurry liquid drops by using a Water-Film model;
specifically, the modified Slinn formula is expressed as follows:
in the middle ofAndthe diffusion, interception and inertial mechanisms respectively, are directed to the trapping efficiencyThe calculation formula of the contribution of (a) is as follows:
=
wherein,
is a Reynolds number;schmitt number for fly ash particles;stokes number of fly ash particles;is a critical stokes number;
the final falling speed of the slurry; wherein a is a group of the total number,is a constant, a=842, =0.8；is the particle size ratio of fly ash particles and slurry liquid drops;is the viscosity ratio of slurry and flue gas;
the particle size of the fly ash particles;is the grain size of the slurry;is the diffusion coefficient of fly ash particles;is the viscosity of the slurry;is the viscosity of the flue gas;
is the density of fly ash particles;is slurry density;is the density of the flue gas;is the standard smoke density;is the relaxation time of the particles;is the grain size of the slurryTo the power.
The Water-film model is a mathematical model built in CFD software, and the situation that discrete liquid drops form a continuous liquid film can be calculated through the model, so that liquid drops which escape without forming the liquid film can be calculated.
S5, taking the flue gas flow velocity distribution, the temperature distribution and the dust particle size distribution at the inlet section of the pre-washing tower as boundary conditions, taking the collection efficiency curves of the demister in the pre-washing tower for dust particles and slurry liquid drops with different particle sizes as input conditions, and carrying out gas-liquid-solid three-phase flow simulation calculation on the pre-washing tower to obtain the amounts of the dust particles and the slurry liquid drops with different particle sizes, which escape from the outlet of the pre-washing tower.
In the implementation, when CFD calculation of the integral synergistic removal effect is carried out on the pre-washing tower, a porous medium model is adopted in the demister area, the size distribution of slurry at the nozzle outlet of the spraying layer is set according to the designed size distribution of the nozzle, and the size distribution can be set according to the size distribution provided by a nozzle manufacturer; the efficiency of the spraying layer area for removing dust particles is calculated by comprehensively considering the interaction of gas, liquid and solid phases through a Slin formula, and the efficiency of the spraying layer area for removing dust particles with different particle diameters is calculated by using a Water-Film model; meanwhile, the capturing efficiency of the demister on dust particles and slurry liquid drops with different particle sizes is calculated integrally on the pre-washing tower in a mode that a demister efficiency model of the pre-washing tower is taken as a sub-model, and the amounts of the dust particles and the slurry liquid drops with different particle sizes escaping from the outlet of the pre-washing tower are obtained.
S6, establishing a demister model in the absorption tower and performing detailed gas-solid-liquid three-phase flow simulation calculation to obtain a trapping efficiency curve of the demister in the absorption tower on dust particles and slurry liquid drops with different particle diameters.
S7, taking the flue gas flow velocity distribution, the temperature distribution, the dust particle size distribution and the amounts of dust particles and slurry droplets in different particle sizes escaping from the outlet of the pre-washing tower at the inlet section of the absorption tower as boundary conditions, taking the trapping efficiency curves of the demister in the absorption tower on the dust particles and the slurry droplets in different particle sizes as input conditions, and carrying out gas-liquid-solid three-phase flow simulation calculation on the absorption tower to obtain the amounts of the dust particles and the slurry droplets in different particle sizes escaping from the outlet of the absorption tower.
In the implementation, the process of demister model in the absorption tower and performing detailed gas-liquid-solid three-phase flow simulation calculation and gas-liquid-solid three-phase flow simulation calculation on the whole absorption tower is the same as the principle of the pre-washing tower, and the detailed description is omitted here.
S8, calculating the sum of the amounts of dust particles escaping from the outlet of the absorption tower and the solid content of slurry liquid drops under different particle sizes so as to determine the synergistic removal effect.
In the implementation, aiming at the non-operated tower-type flue gas wet desulfurization device, the solid content is calculated according to 15%; and carrying out actual test acquisition on field production data aiming at the series-tower type flue gas wet desulfurization device which is put into operation.
Examples
Step one, establishing a two-stage serial tower flue system integral model and collecting corresponding operation condition parameters, wherein the two-stage serial tower flue system three-dimensional model is provided with two fans at the inlet flue of the pre-washing tower as shown in fig. 3, and the operation condition parameters are shown in the table one:
list one
| Unit | Value | |
| Unit scale | MW | 660 |
| Inlet smoke volume | Nm 3 /h | 2370000 |
| Inlet flue gas temperature | ℃ | 130 |
| Diameter of prewash tower | m | 16.5 |
| Pre-wash tower height | m | 35 |
| Spray layer number of pre-washing tower | 3 | |
| Pre-wash tower inlet dust concentration | mg/Nm 3 | 50 |
| Diameter of absorption tower | m | 16.5 |
| Absorption tower height | m | 37 |
| Spray layer number of absorption tower | 4 |
Step two, single-phase flow simulation calculation is carried out on the two-stage series-connected absorption tower flue system, and flow field distribution of the two-stage series-connected absorption tower flue system is obtained.
Step three, intercepting inlet cross sections of a pre-washing tower and an absorption tower, and respectively obtaining flue gas flow velocity distribution, temperature distribution and dust particle size distribution; the flue gas flow velocity distribution at the inlet section of the pre-washing tower is shown in fig. 4, and the flue gas flow velocity distribution at the inlet section of the absorption tower is shown in fig. 5.
Step four, establishing a demister model in the pre-washing tower and carrying out detailed gas-solid-liquid three-phase flow simulation calculation to obtain a trapping efficiency curve of the demister in the pre-washing tower on dust particles with different particle diameters and slurry liquid drops; in the simulation calculation process, a model of the demister in the pre-washing tower is shown in fig. 6, grid division is shown in fig. 7, and the efficiency curves of the demister in the pre-washing tower for trapping dust particles with different particle diameters are shown in fig. 8, wherein the efficiency curves of the dust particles with different particle diameters under three speeds of 3.5m/s, 4.0m/s and 4.5m/s are shown; the slurry drop capturing efficiency curves are shown in FIG. 9, in which the slurry drop capturing efficiency curves of different particle diameters at three speeds of 3.5m/s, 4.0m/s and 4.5m/s are shown.
And fifthly, performing gas-liquid-solid three-phase flow simulation calculation on the pre-washing tower to obtain the amounts of dust particles and slurry liquid drops escaping from the outlet of the pre-washing tower under different particle diameters, wherein the track of the dust particles in the pre-washing tower is shown in fig. 10, and the track of the slurry liquid drops is shown in fig. 11 in the simulation calculation.
Step six, carrying out detailed gas-solid-liquid three-phase flow simulation of a submodel on the demister in the absorption tower to obtain trapping efficiency curves of dust with different particle diameters and slurry liquid drops, wherein in simulation calculation, the trapping efficiency curves of dust particles of the demister in the absorption tower are shown as a graph in FIG. 12, and the trapping efficiency curves of dust particles with different particle diameters at three speeds of 3.5m/s, 4.0m/s and 4.5m/s are shown; the slurry droplet collecting efficiency curves are shown in FIG. 13, in which the slurry droplet collecting efficiency curves of different particle diameters at three speeds of 3.5m/s, 4.0m/s and 4.5m/s are shown.
And seventhly, performing gas-liquid-solid three-phase flow simulation calculation on the absorption tower to obtain the amounts of dust particles and slurry liquid drops escaping from the outlet of the absorption tower under different particle diameters, wherein in the simulation calculation, the track of the dust particles in the absorption tower is shown in fig. 14, and the track of the slurry liquid drops in the absorption tower is shown in fig. 15.
Step eight, adding slurry liquid drops at the outlet of the absorption tower with the dust particle amount at the outlet of the absorption tower according to the solid content of a certain proportion to obtain the solid particle emission concentration at the outlet of the two-stage series absorption tower.
After the simulation calculation, counting the concentration distribution of the particulate matters at different positions of the two-stage serial tower type flue gas wet desulfurization device to obtain a distribution diagram shown in fig. 16; the dust concentration at the outlet of the absorption tower was calculated to be 2.8mg/Nm 3 The slurry drop concentration was 12.2mg/Nm 3 The solids concentration at the outlet of the absorption column was 1.83mg/Nm as a result of carrying the slurry, calculated as 15% solids in the recycled slurry 3 The method comprises the steps of carrying out a first treatment on the surface of the The total discharge concentration of the two is 4.63mg/Nm 3 Meets the emission standard.
According to the scheme provided by the invention, the flue system, the demister, the pre-washing tower and the absorption tower are respectively subjected to simulation calculation step by step in an integral-local-integral mode; the flow velocity distribution and the temperature distribution of inlet sections of the pre-washing tower and the absorption tower are rapidly obtained by adopting single-phase flow integral simulation; acquiring the trapping efficiency curves of the pre-wash tower demister and the absorption tower demister on dust particles and liquid drop slurry with different particle diameters by adopting calculation of a demister submodel; on the basis of the two steps, three-phase flow collaborative removal simulation calculation of the flow in the pre-washing tower and the absorption tower can be performed, and the particle collaborative removal effect of the two-stage serial tower flue gas wet desulphurization device can be rapidly and quantitatively calculated; compared with the conventional integral simulation calculation method, the method can enable the numerical calculation of the cooperative removal of the particulate matters to be possible, and obtain accurate calculation results.
The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.
Claims (8)
1. A calculation method for the cooperative particulate removal effect of a serial tower type flue gas wet desulfurization device is characterized by comprising the following steps:
s1, establishing a two-stage serial tower flue system integral model and collecting two-stage serial tower flue system operation condition parameters;
s2, performing single-phase flow simulation calculation on the two-stage serial tower flue system by using the established integral model to obtain flow field distribution of the two-stage serial tower flue system;
s3, intercepting inlet sections of the pre-washing tower and the absorption tower, and respectively acquiring flue gas flow velocity distribution, temperature distribution and dust particle size distribution at the inlet sections according to the obtained flow field distribution;
s4, establishing a demister model in the pre-washing tower and performing detailed gas-solid-liquid three-phase flow simulation calculation to obtain a trapping efficiency curve of the demister in the pre-washing tower on dust particles with different particle diameters and slurry liquid drops;
s5, taking flue gas flow velocity distribution, temperature distribution and dust particle size distribution at the inlet section of the pre-washing tower as boundary conditions, taking a collection efficiency curve of a demister in the pre-washing tower for dust particles and slurry liquid drops with different particle sizes as input conditions, and carrying out gas-liquid-solid three-phase flow simulation calculation on the pre-washing tower to obtain the amounts of the dust particles and the slurry liquid drops with different particle sizes, which escape from the outlet of the pre-washing tower;
s6, establishing a demister model in the absorption tower and performing detailed gas-solid-liquid three-phase flow simulation calculation to obtain a trapping efficiency curve of the demister in the absorption tower on dust particles and slurry liquid drops with different particle diameters;
s7, taking the flue gas flow velocity distribution, the temperature distribution, the dust particle size distribution and the amounts of dust particles and slurry droplets in different particle sizes escaping from the outlet of the pre-washing tower at the inlet section of the absorption tower as boundary conditions, taking the trapping efficiency curves of the demister in the absorption tower on the dust particles and the slurry droplets in different particle sizes as input conditions, and carrying out gas-liquid-solid three-phase flow simulation calculation on the absorption tower to obtain the amounts of the dust particles and the slurry droplets in different particle sizes escaping from the outlet of the absorption tower;
s8, calculating the sum of the amounts of dust particles escaping from the outlet of the absorption tower and the solid content of slurry liquid drops under different particle sizes so as to determine the synergistic removal effect.
2. The method for calculating the cooperative particulate removal effect of a serial-tower type flue gas wet desulfurization device according to claim 1, wherein the system operation condition parameters in S1 comprise: inlet flue gas amount, inlet flue gas temperature, pre-scrubber diameter, pre-scrubber height, number of spray layers of pre-scrubber, pre-scrubber inlet dust concentration, absorber diameter, absorber height, and number of spray layers of absorber.
3. The method for calculating the cooperative particulate removal effect of the serial-tower type flue gas wet desulfurization device according to claim 1, wherein in the single-phase flow simulation calculation process of the two-stage serial-tower flue system in the step S2, a turbulence model component transportation model is selected to perform simulation calculation on flue gas flow of a flue, a Lagrange discrete phase model is adopted to perform simulation calculation on dust particles, and a calculation domain is from a fan outlet to a chimney inlet and comprises a connecting flue, a prewash tower body and an absorber body.
4. The method for calculating the cooperative particulate removal effect of the serial-tower type flue gas wet desulfurization device according to claim 1, wherein in the step S4, in the detailed gas-solid-liquid three-phase flow simulation calculation process, the dust particulate removal uses a Slin formula to comprehensively consider the interaction of gas, liquid and solid phases, the removal efficiency of the demister in the pre-washing tower to dust particulates with different particle diameters is calculated, and the removal efficiency of slurry liquid drops is calculated by using a Water-Film model.
5. The method for calculating the synergistic particulate removal effect of a serial wet flue gas desulfurization device according to claim 4, wherein the Slinn formula is expressed as follows:
；
in the middle ofAnd->The diffusion, interception and inertial mechanisms respectively, are directed to the trapping efficiencyThe calculation formula of the contribution of (a) is as follows:
；
=/>；
；
wherein,
；
；
；
；
；
；
；
is a Reynolds number; />Schmitt number for fly ash particles; />Stokes number of fly ash particles; />Is a critical stokes number;
the final falling speed of the slurry; wherein a, & gt>As a constant, a=842, < >> =0.8；/>Is the particle size ratio of fly ash particles and slurry liquid drops; />Is the viscosity ratio of slurry and flue gas;
the particle size of the fly ash particles; />Is the grain size of the slurry; />Is the diffusion coefficient of fly ash particles; />Is the viscosity of the slurry; />Is the viscosity of the flue gas;
is the density of fly ash particles; />Is slurry density; />Is the density of the flue gas; />Is the standard smoke density; />Is the relaxation time of the particles; />Is>To the power.
6. The method for calculating the cooperative particulate removal effect of the tower-type flue gas wet desulfurization device according to claim 5, wherein in the step S5, in the process of carrying out gas-liquid-solid three-phase flow simulation calculation on the pre-wash tower, a porous medium model is adopted in a demister area, slurry particle size distribution at a spray layer nozzle outlet is set according to nozzle design particle size distribution, the interaction of gas-liquid-solid three phases is comprehensively considered by using a Slin formula in the spray layer area to remove dust particles, the removal efficiency of the spray layer area to dust particles with different particle sizes is calculated, and the removal efficiency of slurry liquid drops is calculated by using a Water-Film model.
7. The method for calculating the synergistic removal effect of particulate matters in a serial-tower type flue gas wet desulfurization device according to claim 2, wherein the inlet flue gas amount is the sum of outlet flue gas amounts comprising all fans; aiming at the non-operational serial tower type flue gas wet desulfurization device, the inlet flue gas temperature can be obtained according to design parameters and similar project test data; aiming at the series-tower type flue gas wet desulfurization device which is put into operation, the inlet flue gas temperature can be obtained according to on-site monitoring data.
8. The method for calculating the synergistic removal effect of particulate matters of the serial-tower type flue gas wet desulfurization device according to claim 1, wherein the solid content is calculated according to 15% for the serial-tower type flue gas wet desulfurization device which is not put into operation; and carrying out actual test acquisition on field production data aiming at the series-tower type flue gas wet desulfurization device which is put into operation.
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