Cyclone separator, pulverized coal separation system and cyclone separator structure optimization method

Abstract

The invention relates to the technical field of pulverized coal separation, in particular to a cyclone separator, a pulverized coal separation system and a cyclone separator structure optimization method.The cyclone separator comprises an air inlet unit which comprises an air inlet assembly and a separation assembly connected with the air inlet assembly; and the discharge unit comprises an exhaust assembly arranged on the inner side of the separation assembly and a dust discharge assembly arranged at the bottom of the separation assembly. The cyclone separator has the beneficial effects that by arranging the spiral channel, the centrifugal force after dust-containing gas enters can be increased, the dust particle separation efficiency is improved, the longitudinal circulation phenomenon at the top of the separator can be effectively avoided, the influence of a top ash ring is relieved, and mutual interference of airflow in adjacent inner and outer rotational flows is avoided; and the number of particles of large-particle-size dust entering the exhaust pipe through longitudinal circulation is reduced, the flow field can be stabilized, the separation performance is improved, and the separation efficiency of small-particle-size dust is improved.

Description

Technical Field

[0001] The invention relates to the technical field of coal powder separation, in particular to a cyclone separator, a coal powder separation system and a cyclone separator structure optimization method. Background Art

[0002] The existence of local secondary flow inside the cyclone separator causes its internal three-dimensional velocity field to present a non-axisymmetric structure, which has an adverse effect on the gas-solid two-phase separation. Therefore, it is a problem today to analyze its internal flow field and study its relationship with performance parameters. Especially for fine particles with a diameter of less than 20μm, the separation efficiency is less than 80%. Korean scholars Xun Sun et al. used the response surface model combined with genetic algorithm to conduct structural optimization research on the straight-cut inlet separator, and compared the separation effect of the optimized model with the original model for particles in the range of 1 to 5μm. The results showed that the optimized model can only increase the efficiency by 11.67%. In addition, Swedish scholar Misiulia et al. published a journal paper and concluded that when the optimal inlet angle of a spiral inlet cyclone separator with a barrel diameter of 2400mm is 20°, the separator has the greatest aerodynamic efficiency. However, no research was conducted on the separation efficiency of the separator for fine particles at the optimal angle; Chinese scholar Sun Guogang et al. published a journal paper proposing to add a guide plate in the annular space of the spiral inlet cyclone separator to stabilize the internal flow field of the separator, and obtained the optimal number of turns of the spiral guide plate to be 2, and analyzed the efficiency of silicon powder particles with a particle size range of 0.5 to 100 μm. Although the efficiency can eventually reach about 94%, compared with the general flat-top structure, the efficiency is only increased by 2 to 3%. Obviously, in the face of the efficiency of the particle size span of 100 μm, the improvement of this structure is very small, and there is no particle size analysis, so there is no way to know the efficiency of particles with a particle size less than 20 μm. Therefore, an optimization scheme is still needed to improve the separation performance of the separator for fine particles of 1 to 20 μm. Summary of the invention

[0003] In view of the above problems or problems existing in the prior art, the present invention is proposed.

[0004] Therefore, the object of the present invention is to provide a cyclone separator, which can improve the separation ability of the separator for fine particles of 1 to 20 μm. It includes an air inlet, an air inlet channel extending inwardly from the air inlet, and a spiral channel extending spirally along the extension direction of the air inlet channel;

[0005] The spiral channel is improved from a flat-top type to a spiral channel with one spiral turn, and the air inlet angle is changed from a horizontal entry angle to the same angle as the air inlet, that is, a 26° entry angle;

[0006] The separation assembly includes a cylindrical separation cavity fixedly connected to the outer wall of the spiral channel, and an inverted cone separation cavity fixedly connected to the bottom of the cylindrical separation cavity;

[0007] The ratio of the cavity height to the diameter of the cylindrical separation cavity of the cylindrical separation cavity and the inverted cone separation cavity is increased to 4;

[0008] The exhaust assembly includes an exhaust passage arranged inside the cylindrical separation chamber, and an exhaust port arranged on one side of the exhaust passage;

[0009] The ratio of the exhaust channel diameter to the cylindrical separation chamber diameter is reduced to 0.54, and the ratio of the exhaust port diameter to the cylindrical separation chamber diameter is reduced to 0.42;

[0010] The dust exhaust assembly includes a dust exhaust port disposed at the bottom of the inverted cone-shaped separation chamber, and a dust collecting channel fixedly connected to the dust exhaust port;

[0011] The ratio of the dust outlet diameter to the cylindrical separation chamber diameter is reduced to 0.37.

[0012] In view of the fact that in actual use, there is still a problem that the coal powder is not screened thoroughly and the coal powder cannot be fully burned during combustion.

[0013] To solve the above technical problems, the present invention also provides the following technical solutions: a coal powder separation system, comprising a coarse classification module connected to an air inlet unit, a grinding module connected to the coarse classification module, a feeding module connected to the grinding module, a combustion module connected to an emission unit, and a dust collection module connected to a dust exhaust unit.

[0014] As a preferred solution of the pulverized coal separation system of the present invention, the separation system further comprises a regulating module connected to the air inlet unit, and a control module connected to the regulating module.

[0015] As a preferred solution of the coal powder separation system suitable for fine coal powder separation in power plants of the present invention, the coarse classification module includes a coarse powder separator; the grinding module includes a ball mill; the feeding module includes a feeding hopper; the combustion module includes a boiler furnace; the dust collection module includes a coal ash bucket; the regulating module includes a regulating valve; and the control module includes a control terminal.

[0016] As a preferred solution of the coal powder separation system of the present invention, the regulating modules are respectively arranged at the inlet and outlet ends of the cyclone separator and at the outlet of the feed module to adaptively control the feed flow rate, the discharge rate of dust particles and the discharge rate of residual gas, and floating flow meters are respectively arranged at the inlet of the coarse separation module and the cyclone separator to monitor the incoming flow in real time.

[0017] In actual use, there is still a problem that the separator structure cannot adapt well to the coal powder separation scenario.

[0018] In order to solve the above technical problems, the present invention also provides the following technical solutions: a method for optimizing the structure of a cyclone separator, comprising analyzing the flow field distribution inside the separator through a coupling model of fluid mechanics and discrete phases, predicting the trajectory of dust particles, and calculating the inlet and outlet pressure drop and separation efficiency;

[0019] The exhaust pipe diameter, dust outlet diameter, cone height, exhaust pipe insertion depth and inlet velocity are taken as design variables, and dimensionless according to the cylinder diameter. The separation efficiency and total pressure drop are taken as response targets, and a second-order polynomial response surface model is established, which is used as the fitness function of the genetic algorithm.

[0020] The genetic algorithm toolbox of Matlab software is used to solve the fitness function of separation efficiency and total pressure drop. Taking maximum efficiency and minimum pressure drop as the goals, a series of optimal solution sets are obtained under the common constraints of five design variables.

[0021] As a preferred solution of the cyclone separator structure optimization method of the present invention, wherein: the coupling model includes:

[0022] The RSM turbulence model was selected to simulate the complex flow field inside the cyclone separator;

[0023] According to the model constants σk, C1, C2, the RSM turbulence model is used to simulate the flow field inside the cyclone separator. The gas phase fluid velocity is represented by u. The gas phase flow field inside the cyclone separator is calculated by the following formula, where the constants are usually taken as σk = 1, C1 = 1.8, C2 = 0.6;

[0024]

[0025] Among them, P and Vt in the above formula represent turbulent kinetic energy and kinematic viscosity respectively, and the upper and lower eddy currents in the separator are described by Pij, and the constant Cu is taken as 0.9. The values ​​of P, Vt and Pij are as follows:

[0026]

[0027]

[0028]

[0029] As a preferred solution of the cyclone separator structure optimization method of the present invention, wherein: the RSM turbulence model also includes:

[0030] The calculation formula of the gas phase flow field inside the cyclone separator is as follows: ε represents the turbulent dissipation rate, K represents the measure of the development of turbulent motion in the separator, and the constants ε = 1.3, Cε1 = 1.44, Cε2 = 1.92, where ε and K are calculated according to the following equations:

[0031]

[0032]

[0033] In the above formula, Rij represents the Reynolds shear stress and xi is the position vector; according to the calculated quantity, u' represents the fluid fluctuation velocity, is the average flow velocity; ρ is the gas phase fluid density, is the time-averaged pressure, ui and uj are the components of the fluid velocity, which are used to calculate Rij to close the Reynolds-averaged Navier-Stokes equation, which is as follows:

[0034]

[0035]

[0036]

[0037]

[0038] As a preferred solution of the cyclone separator structure optimization method of the present invention, wherein: the second-order polynomial response surface model includes:

[0039] The obtained response values ​​were fitted with the simulated data using statistical and mathematical methods based on the least squares method to obtain the following multivariate quadratic regression equation:

[0040]

[0041] Among them, Yn is the response variable, n=1 represents pressure drop, n=2 represents separation efficiency; b0, bi, bij, bii are intercept, linear coefficient, interaction coefficient, quadratic term coefficient respectively; xi, xj are design variables respectively, i, j=1, 2, 3, 4, 5, corresponding to the five main structural parameters of the separator to be studied: exhaust pipe diameter, dust outlet diameter, cone height, exhaust pipe insertion depth and inlet velocity.

[0042] As a preferred solution of the cyclone separator structure optimization method of the present invention, wherein: the Matlab software genetic algorithm includes:

[0043] With the maximum efficiency and minimum pressure drop as the goal, a series of optimal solution sets are obtained under the common constraints of the five design variables. The calculation method is as follows:

[0044]

[0045]

[0046] Among them, the constraints of the fitness function and the five design variables are as follows:

[0047] Minimum voltage drop Y1(x1,x2,x3,x4,x5)

[0048] Maximum efficiency Y2(x1,x2,x3,x4,x5)

[0049] Constraint (0.4 <x1<0.6)

[0050] (0.2 <x2<0.4)

[0051] (2 <x3<4)

[0052] (0.5 <x4<1.5)

[0053] (12 <x5<20)

[0054] The optimal solution set calculated under the above conditions, each solution corresponds to a combination of design parameters.

[0055] The beneficial effects of the present invention are as follows: the present invention can increase the centrifugal force after the dust-laden gas enters through the setting of the spiral channel, improve the dust particle separation efficiency, and can also effectively avoid the longitudinal circulation phenomenon at the top of the separator, reduce the influence of the "top ash ring", avoid the mutual interference of the airflows in adjacent inner and outer swirls, and reduce the number of particles of large-size dust entering the exhaust pipe through the longitudinal circulation, which helps to stabilize the flow field, improve the separation performance, and improve the separation efficiency of small-size dust. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0057] Figure 1 This is a schematic diagram of the complete structure of the cyclone separator.

[0058] Figure 2 Comparison chart of the original model and optimized model of cyclone separator.

[0059] Figure 3 A plot of pressure drop versus efficiency after multi-objective optimization of a cyclone separator.

[0060] Figure 4 Static pressure contour diagram of the original model and optimized model of the cyclone separator.

[0061] Figure 5Simulation diagram of particle trajectories for the original model and optimized model of the cyclone separator.

[0062] Figure 6 This is the single factor change benefit curve of the cyclone separator.

[0063] Figure 7 This is the first implementation structure diagram of the coal powder separation system.

[0064] Figure 8 This is the second implementation structure diagram of the coal powder separation system. DETAILED DESCRIPTION

[0065] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0066] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0067] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0068] Example 1

[0069] Reference Figure 1 to Figure 5 , which is the first embodiment of the present invention, provides a cyclone separator, which can improve the separation performance of the separator for fine particles of 1 to 20 μm.

[0070] Specifically, the air inlet assembly 101 includes an air inlet 101a, an air inlet channel 101b extending inwardly from the air inlet 101a, and a spiral channel 101c extending spirally along the extending direction of the air inlet channel 101b;

[0071] The inlet angle of the air inlet 101a is 26°, and the number of spiral turns of the spiral channel 101c is 1.

[0072] It should be noted that the angle of the air inlet 101a is set to 26°. The present invention changes the structure at the inlet of the separator from a flat top to a spiral shape, and its spiral angle remains consistent with the inlet angle. At the same time, the number of spiral turns is increased by 1, which ensures that the dust-laden gas can enter the separator from the transport pipeline unimpeded, thereby avoiding energy loss caused by the collision of the airflow with the wall. At the same time, the number of spiral turns is 1, which also ensures that the initial movement trend of the dust-laden gas is spiral downward, thereby enhancing the external vortex effect generated by the high-speed rotation of the airflow between the cylinder and the exhaust pipe, forcing the airflow to move downward; at the same time, the spiral top structure can effectively avoid the longitudinal circulation phenomenon at the top of the separator, reduce the influence of the "top ash ring", avoid mutual interference of the airflows in adjacent internal and external vortices, and reduce the number of particles entering the exhaust pipe through the longitudinal circulation, which helps to stabilize the flow field and improve the separation performance.

[0073] Furthermore, the separation assembly 102 includes a cylindrical separation chamber 102a fixedly connected to the outer wall of the spiral channel 101c, and an inverted cone separation chamber 102b fixedly connected to the bottom of the cylindrical separation chamber 102a;

[0074] The ratios of the cavity height of the cylindrical separation cavity 102a and the inverted cone separation cavity 102b to the diameter of the cylindrical separation cavity 102a are both increased to 4.

[0075] Furthermore, the exhaust assembly 201 includes an exhaust passage 201a disposed inside the cylindrical separation chamber 102a, and an exhaust port 201b disposed on one side of the exhaust passage 201a;

[0076] The ratio of the diameter of the exhaust channel 201a) to the diameter of the cylindrical separation chamber 102a is reduced to 0.54, and the ratio of the diameter of the exhaust port 201b to the diameter of the cylindrical separation chamber 102a is reduced to 0.42.

[0077] Furthermore, the dust exhaust assembly 202 includes a dust exhaust port 202a disposed at the bottom of the inverted cone-shaped separation chamber 102b, and a dust collection channel 202b fixedly connected to the dust exhaust port 202a, wherein the setting of the sinking channel replaces the setting of the dust collecting hopper, preventing the dust particles from being unable to touch the bottom and being collected due to the shallow bottom of the dust collecting hopper, but increasing the probability of following the gas to rise to the exhaust channel 201a;

[0078] The ratio of the diameter of the dust exhaust port 202a to the diameter of the cylindrical separation chamber 102a is reduced to 0.37.

[0079] When in use, the dust-laden gas enters from the air inlet 101a, enters the spiral channel 101c along the air inlet channel 101b, and when passing through the spiral channel 101c, the dust-laden gas enters the columnar separation chamber 102a along the spiral channel 101c, which reduces the collision of the dust-laden gas with the inner wall of the columnar separation chamber 102a when entering at high speed, and increases the centrifugal force, so that the dust particles therein are completely thrown to the inner wall of the columnar separation chamber 102a by the centrifugal force, and slide down along the columnar separation chamber 102a. When the dust particles slide to the columnar separation chamber When the dust particles reach the bottom of the body 102a, the dust particles are concentrated along the inverted cone separation chamber 102b to the dust exhaust port 202a, and slide into the dust collecting channel 202b through the dust collecting port. At the same time, the dust-laden gas gradually reduces the dust particle content during the spiral entry process until it rotates to the upper side of the dust exhaust port 202a. The remaining gas from which the dust particles are completely separated is converted from outward rotation to inward rotation, and moves upward during the inward rotation, so that the remaining gas is discharged upward through the exhaust channel 201a to the dust exhaust port 202a, and the remaining gas is discharged through the dust exhaust port 202a.

[0080] The flow field inside the cyclone separator is a non-axisymmetric three-dimensional strongly rotating turbulent flow field. CFD simulation technology is used to simulate its complex internal flow field. The commonly used turbulence models are the Reynolds stress model (RSM), the RNG k-ε model, and the large eddy model (LES). The RSM takes into account the anisotropy of turbulence and can more accurately reflect the flow field distribution inside the cyclone separator compared to the RNG k-ε model. The separation performance and flow field distribution obtained have small errors with the experimental data; and the RSM can save computing resources and has a lower computing cost than the LES. Therefore, the RSM turbulence model is selected in the simulation process to calculate the gas phase flow field inside the cyclone separator. The RSM model transport equation is expressed by equation (1):

[0081]

[0082] Where, the subscripts i, j, k are Cartesian coordinates, t is time; ij is the Kronecker function, if i = j, ij = 1; if i ≠ j, then ij = 0. σk, C1, C2 are model constants: σk = 1, C1 = 1.8, C2 = 0.6. u represents the velocity of the gas phase fluid.

[0083] P and Vt represent the turbulent kinetic energy and kinematic viscosity, respectively expressed by equations (2) and (3):

[0084]

[0085] Where the constant Cu is 0.9; Pij is used to describe the up and down vortex motion in the separator, which can be expressed by equation (4):

[0086]

[0087] ε is the turbulent dissipation rate, which is calculated according to equations (5) and (6):

[0088]

[0089] Where K represents the measure of the development of turbulent motion in the separator; the constant ε is 1.3, Cε1 is 1.44, and Cε2 is 1.92.

[0090] The turbulent motion inside the separator is solved using the continuity equation and the Reynolds-averaged Navier-Stokes equations, which are given by equations (7) to (11):

[0091]

[0092]

[0093]

[0094]

[0095] Where Rij represents the Reynolds shear stress, xi is the position vector, u' represents the fluid fluctuation velocity, is the average flow velocity; ρ is the gas phase fluid density, is the time-averaged pressure, ui and uj are the components of the fluid velocity, which are used to calculate Rij to close the Reynolds-averaged Navier-Stokes equation.

[0096] Specifically, Figure 4 As shown, the distribution of static pressure inside the original model and optimized model of the separator obtained by CFD numerical simulation. Red represents high-pressure areas, and light green represents low-pressure areas. From the wall of the separator to the center, the color of the cloud map changes from dark to light, which means that the pressure in the separator gradually decreases. The cyclone separator designed by the present invention presents an obvious pressure difference boundary line inside, and the axial symmetry is better than that of the original cyclone separator, that is, the flow field distribution is more regular; the radial pressure gradient of the optimized model increases, the maximum pressure appears near the wall, and according to Figure 4 The diagrams before and after the optimization show that compared with the original model, the maximum pressure of the optimized model is reduced by about 760Pa, and the pressure in the center of the cylinder is reduced by about 300Pa. At the same time, the proportion of high-pressure areas near the wall increases by about 20%, which expands the downward vortex area near the wall and reduces the upward vortex in the center area, so that more airflow can move to the bottom of the separator, which helps to improve the separation efficiency. The downward vortex can convert more static pressure into dynamic pressure, converting it into a more powerful vortex, which promotes the downward vortex. Therefore, in the static pressure cloud map, the static pressure near the wall is higher and the static pressure in the center area is lower.

[0097] The improvement of separation efficiency can be reflected based on the simulation of particle phase.

[0098] Specifically, the Euler-Lagrangian method is selected for the simulation of the particle phase to track the particle trajectory. This method regards the particles as discrete phases and the gas phase as continuous phases, selects the single-phase coupling mode, and turns on the discrete random walk model to consider the influence of turbulent fluctuations on the particles. The particles are mainly affected by the drag and gravity field in the flow field, so the movement of the particles can be expressed by equations (12) and (13):

[0099]

[0100] where up and p are the particle velocity and density, u is the fluid velocity, xp is the particle path, g is the gravitational acceleration, and Fd is the drag force, calculated according to equation (14):

[0101]

[0102] Cd is the drag coefficient, which can be solved by equation (15) for spherical particles:

[0103]

[0104] Where a1, a2, and a3 are constants. Rep is the particle Reynolds number, defined as equation (16):

[0105]

[0106] Where dp is the particle diameter and is the fluid viscosity.

[0107] The pressure drop is calculated by the pressure difference between the inlet and the outlet obtained by CFD simulation, and the separation efficiency is calculated by the capture efficiency of particles at the dust outlet, that is, equations (17) and (18):

[0108] Δp=p in -p out (17)

[0109] Where p is the static pressure drop, pin and pout are the pressures measured at the separator inlet and outlet, respectively. Similarly,

[0110]

[0111] Among them, refers to the total efficiency of the separator, Ntrapped and Ninjected are the number of particles captured at the dust outlet and the number of particles injected at the inlet, respectively.

[0112] like Figure 5As shown in the figure, the trajectories of particles with a size of 1 to 20e-6m predicted by the simulation calculation of the original separator model and the optimized model. The red lines represent large-size particles (larger than 1.43e-5m), and the blue lines represent small-size particles (smaller than 6.7e-6m). Since the particles affected by the downward swirling airflow in the original model will be affected by the dust hopper, few particles can successfully reach the bottom of the dust hopper and be captured. More large-size particles move upward under the action of the upward swirling airflow, increasing the number of large-size particles on the upper side of the exhaust passage 201a. Figure 4 As shown on the left, at the separator exhaust channel 201a, large-diameter particles (greater than 1.43e-5m) are the majority, with the largest particle size being 1.8e-5m. The optimization model improves the effect of the dust hopper by changing the particle capture surface in the discrete phase model from the bottom surface of the dust hopper to the bottom surface of the cone, i.e., the dust outlet 202a. Figure 5 As shown on the right, compared to Figure 5 Left, at the location of the exhaust channel 201a, the number of particles larger than 1.43e-5m is significantly reduced; at the same time, the particle size of the exhaust channel 201a is basically less than 8.6e-6m, and the maximum particle size is reduced to 1.05e-5m. This shows that the optimization model reduces the escape rate of large-size particles at the exhaust port 201b, allowing the separator to separate finer particles and achieve performance optimization.

[0113] like Figure 3 As shown in Figure 1, the distribution of 50 non-dominated optimization design points for pressure drop and efficiency function by genetic algorithm based on multi-objective optimization clearly shows the trade-off between pressure drop and overall efficiency, and the appropriate separator design can be obtained by considering the compromise. Each data point represents a higher value of the corresponding optimization scheme objective corresponding to a lower value of another objective. The two points A and E marked in the figure respectively indicate the design that gives priority to the lowest pressure drop (the pressure drop at point A is 510.48Pa, and the separation efficiency is 77.98%) and the highest efficiency (the pressure drop at point E is 2372.72Pa, and the separation efficiency is 86.00%); points B and D sacrifice efficiency to obtain a lower pressure drop and sacrifice pressure drop to improve separation efficiency (the pressure drop at point B is 730.28Pa, and the separation efficiency is 81.31%; the pressure drop at point D is 1788.04Pa, and the separation efficiency is 85.54%); and the area near point C indicates a compromise between pressure drop and separation efficiency (the pressure drop at point C is 1181.15Pa, and the separation efficiency is 83.91%).

[0114] In summary, the setting of the spiral channel 101c can increase the centrifugal force after the dust-laden gas enters, improve the dust particle separation efficiency, and effectively avoid the longitudinal circulation phenomenon at the top of the separator, reduce the influence of the "top ash ring", avoid the mutual interference of the airflows in adjacent internal and external swirls, and reduce the number of large-size dust particles entering the exhaust pipe through the longitudinal circulation, which helps to stabilize the flow field, improve the separation performance, and improve the separation efficiency of small-size dust.

[0115] Example 2

[0116] Reference Figure 7-8 , which is the second embodiment of the present invention, provides a coal powder separation system, which can refine the coal powder to an optimal size and make the coal powder burn more completely.

[0117] Specifically, the separation system M includes a coarse separation module 300 connected to the air inlet unit 100, a grinding module 400 connected to the coarse separation module 300, a feeding module 500 connected to the grinding module 400, a combustion module 600 connected to the discharge unit 200, and a dust collection module 700 connected to the dust exhaust unit.

[0118] Furthermore, the separation system M also includes a regulating module 800 connected to the air inlet unit 100 , and a control module 900 connected to the regulating module 800 .

[0119] Furthermore, the coarse classification module 300 includes a coarse powder separator 301; the grinding module 400 includes a ball mill 401; the feeding module 500 includes a feeding hopper 501; the combustion module 600 includes a boiler furnace 601; the dust collection module 700 includes a coal ash bucket 701; the regulating module 800 includes a regulating valve 801; and the control module 900 includes a control terminal 901.

[0120] Preferably, the regulating modules 800 are respectively arranged at both ends of the inlet and outlet of the cyclone separator and at the outlet of the feed module 500 to adaptively control the feed flow rate, the discharge rate of the dust particles and the discharge rate of the residual gas, and floating flow meters are respectively arranged at the inlet of the coarse separation module 300 and the cyclone separator to monitor the incoming flow in real time.

[0121] It should be noted that the control terminal 901 pre-stores a data interval of the applicable range of the flow rate. The floating flow meter transmits real-time monitoring data to the control terminal 901, and the control terminal 901 compares the monitoring data with the pre-stored data. When the monitoring data exceeds the data interval, the control terminal 901 controls the regulating valve 801 to open wider to reduce the dust exhaust pressure. When the monitoring data is lower than the data interval, the control terminal 901 controls the regulating valve 801 to close smaller to prevent the dust falling into the coal ash bucket 701 from being sucked into the separator again.

[0122] The working principle of the system is as follows: the staff starts the control terminal 901, and controls the regulating valve 801 through the control terminal 901, so that the coal powder enters the ball mill 401 from the feed hopper 501 through the regulating valve 801 to adjust the flow rate. The control terminal 901 controls the ball mill 401 according to the program, so that the coal powder is ground into coal powder particles with uniform particle size in the ball mill 401, and further transported to the coarse powder separator 301. The control terminal 901 controls the coarse powder separator 301 to start working, so that the coarse powder separator 301 screens the coal powder into coarse coal powder and fine coal powder according to the difference in particle size and density. The coarse coal powder The fine coal powder (with a diameter greater than 90 μm) is separated out and transported to the ball mill 401 for re-grinding along the reflux pipe at the lower end. The fine coal powder (with a diameter less than 90 μm) is transported from the upper outlet to the cyclone separator. After separation by the cyclone separator, the coal powder particle size suitable for combustion in the boiler furnace 601 is further screened out, so that it follows the air flow through the exhaust channel 201a, and then after the flow is adjusted by the regulating valve 801, it is discharged by the cyclone separator to the inside of the boiler furnace 601 to wait for combustion. The unqualified particle size will be collected in the ash bucket 701 through the dust collecting channel 202b after the flow is adjusted by the regulating valve 801.

[0123] In summary, through the grinding of the ball mill 401, and the cooperation of the coarse powder separator 301 and the cyclone separator, the coal powder is repeatedly ground and screened twice, so that the coal powder burned in the boiler furnace 601 has the optimal particle size, ensuring sufficient combustion of the boiler furnace 601. The cooperation of the control module 900 and the adjustment module 800 can enable the overall system to be remotely controlled while monitoring and adjusting the flow of each part as needed, so that the coal powder screening process can be adjusted more accurately as needed. When the dust discharge volume is large, the valve opening becomes larger to reduce the dust discharge pressure. When the dust discharge volume is small, the valve opening is reduced to prevent the dust falling into the coal ash bucket 701 from being sucked into the separator again.

[0124] Example 3

[0125] Reference Figure 6 , which is the third embodiment of the present invention, provides a cyclone separator structure optimization method, which can optimize the structure of the cyclone separator to best suit the coal powder separation scenario.

[0126] Specifically, the flow field distribution inside the separator is analyzed through the coupling model of fluid mechanics and discrete phase, the dust particle trajectory is predicted, and the inlet and outlet pressure drop and separation efficiency are calculated;

[0127] The exhaust pipe diameter, dust outlet diameter, cone height, exhaust pipe insertion depth and inlet velocity are taken as design variables, and dimensionless according to the cylinder diameter. The separation efficiency and total pressure drop are taken as response targets, and a second-order polynomial response surface model is established, which is used as the fitness function of the genetic algorithm.

[0128] The genetic algorithm toolbox of Matlab software is used to solve the fitness function of separation efficiency and total pressure drop. Taking maximum efficiency and minimum pressure drop as the goals, a series of optimal solution sets are obtained under the common constraints of five design variables.

[0129] It should be noted that the genetic algorithm toolbox of Matlab software is used to solve the fitness function of separation efficiency and total pressure drop, with maximum efficiency and minimum pressure drop as the goals, to obtain a series of optimal solution sets under the common constraints of the five design variables, namely, the solution sets of equations (20) and (21).

[0130]

[0131]

[0132] The fitness function and constraints of the five design variables used in the response surface model and genetic algorithm are as follows:

[0133] Minimum voltage drop Y1(x1,x2,x3,x4,x5)

[0134] Maximum efficiency Y2(x1,x2,x3,x4,x5)

[0135] Constraint (0.4 <x1<0.6)

[0136] (0.2 <x2<0.4)

[0137] (2 <x3<4)

[0138] (0.5 <x4<1.5)

[0139] (12 <x5<20)

[0140] Each solution in the obtained solution set corresponds to a combination of design parameters, which can be selected by practitioners according to actual production needs.

[0141] Specifically, according to the single factor experimental analysis, the control variable method was adopted to carry out single factor CFD simulation calculations on the five design variables studied in turn, and the impact benefit curve of single factor change was obtained with the minimum pressure drop and maximum separator efficiency as the goal.

[0142] In order to establish the functional relationship between the response variable and multiple design factors, a response surface model is generally established. The obtained response value is fitted with the simulation data using statistical and mathematical methods based on the least squares method to obtain a multivariate quadratic regression equation. The general form of the quadratic regression equation in RSM can be expressed as equation (19):

[0143]

[0144] Where: Yn is the response variable, n = 1 represents pressure drop, n = 2 represents separation efficiency; b0, bi, bij, bii are intercept, linear coefficient, interaction coefficient, quadratic term coefficient respectively; xi, xj are design variables respectively, i, j = 1, 2, 3, 4, 5, corresponding to the five main structural parameters of the separator to be studied: exhaust pipe diameter (De), dust outlet diameter (Dt), cone height (Hc), exhaust pipe insertion depth (Hin) and inlet velocity (v). The multivariate quadratic equations of pressure drop and efficiency obtained using Design-Expert experimental analysis software are (20) and (21):

[0145]

[0146]

[0147] Among them, Figure 6 As shown in the figure, with the increase of De / D, the separation efficiency shows a trend of increasing first and then decreasing, and reaches a maximum value in the range of 0.5-0.6, that is, the separation efficiency is optimal. Therefore, it can be preliminarily determined that the De / D value range is (0.5, 0.6). From the influence curve of Dt / D, it is observed that the pressure drop and separation efficiency reach extreme values ​​at 0.32 and 0.4 respectively, and the optimization interval is preliminarily determined to be (0.25, 0.4). Therefore, according to this method, it can be inferred that the optimization interval of Hin / D is (0.6, 1.2). From the influence results of Hc / D, there are no obvious extreme points in separation efficiency and pressure drop. However, when Hc / D=3, the slope of the separation efficiency curve changes suddenly. When Hc / D>3, the slope of the curve increases suddenly. Based on this as a reference point, the optimization interval of Hc / D is determined to be (2, 4). From the analysis of the effect of inlet velocity v, when v=20m / s, the slope of the efficiency curve changes greatly, and when v<20m / s, the efficiency decreases as the speed increases. When v=16m / s, the slope of the curve also changes significantly. Considering that in the actual operation of the equipment, excessive speed may cause vibration and pose a safety hazard. Therefore, after comprehensive consideration, the optimal speed interval is determined to be (12, 20).

[0148] In order to obtain the detailed local size ratio of the spiral surface inlet cyclone separator, the optimal range of the design parameters of the response surface optimization was expanded, and the lower limit of De / D was reduced to 0.4. Since De / D is too small, it is not conducive to the airflow flowing out along the exhaust duct. If it is too large, the probability of "short-circuit flow" will increase, causing the particles to flow out of the separator directly from the exhaust pipe without being separated. Since the optimal movement state of the particles is to flow out from the dust outlet 202a, if Dt / D is too small, it means that the diameter of the dust outlet 202a is reduced, and the corresponding volume flow rate will be reduced. If Dt / D is too large, it will block the flow. The development of the inner vortex that hinders the upward movement of the center area of ​​the separator, causing the dust-laden airflow to flow out of the separator directly from the dust outlet 202a, which violates the working principle of the separator. After comprehensive consideration, the optimization interval of Dt / D is increased to (0.2, 0.4); similarly, a too small Hin / D value means that the exhaust pipe is not inserted deep enough, which will also increase the probability of short-circuit flow. The previous research results show that if the insertion depth is too long, Hin / D>1.6, the overall separation efficiency will be reduced. Therefore, the optimization interval of Hin / D is determined to be (0.5, 1.5). The optimal range of each parameter in the research and development process is finally determined and summarized in Table 1.

[0149] size Geometry Lower limit Upper limit De / D Exhaust channel diameter 0.4 0.6 Dt / D Dust outlet diameter 0.2 0.4 Hc / D Cone height 2 4 Hin / D Exhaust channel insertion depth 0.5 1.5 v(m / s) Inlet speed 12 20

[0150] Table 1 Size constraint values ​​in the response surface model (separator cylinder diameter D = 3200 mm)

[0151] The second-order response polynomial model of pressure drop and separation efficiency established based on the response surface model was used as the fitness function of the genetic algorithm, and the upper and lower limits of the size in Table 1 were used as the constraints of the function. Further, one of the optimization solutions obtained using the multi-objective genetic algorithm toolbox in Matlab was compared with the size of the original model to form Table 2.

[0152]

[0153]

[0154] Table 2 Comparison of models before and after optimization (separator cylinder diameter D = 3200 mm)

[0155] Table 3 shows the performance comparison of the separator before and after optimization. From the simulation calculation results, the pressure drop of the optimized model is reduced by 553.23Pa and the separation efficiency is increased by 6.42% compared with the original model.

[0156] Original Model Optimizing the model Pressure drop(Pa) 1277.29 730.28 Separation efficiency (%) 74.89 81.31

[0157] Table 3 Performance comparison before and after optimization

[0158] In summary, the length of the cylindrical separation chamber of the cyclone separator is optimized by predicting the trajectory of dust particles, and the number of spiral turns and the inlet and outlet size angles are carefully optimized through the cooperation of the response surface model and the genetic algorithm. Through multiple model calculations and the display of simulated images, the cyclone separator structure reaches the optimal solution in the coal powder separation scenario, which greatly improves the separation efficiency and can fully screen out the fully combustible coal to be burned in the boiler furnace.

[0159] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible without substantially departing from the novel teachings and advantages of the subject matter described in the application (e.g., mounting arrangements, use of materials, color, changes in orientation, etc.). For example, the element shown as integrally formed may be composed of a plurality of parts or elements, the position of the element may be inverted or otherwise changed, and the nature or number or position of the discrete element may be altered or changed. Therefore, all such modifications are intended to be included within the scope of the present invention. The order or sequence of any process or method steps may be changed or reordered according to an alternative embodiment. In the claims, any "bracket plus function" clause is intended to cover the structure of the execution function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the present invention is not limited to a specific embodiment, but extends to a variety of modifications that still fall within the scope of the appended claims.

[0160] Additionally, in an effort to provide a concise description of example embodiments, all features of an actual implementation may not be described.

[0161] It should be understood that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but for those of ordinary skill having the benefit of this disclosure, the development effort will be a routine task of design, fabrication, and production without undue experimentation.

[0162] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A cyclone separator, characterized in that: include, The air inlet assembly (101) comprises an air inlet (101a), an air inlet channel (101b) extending inwardly along the air inlet (101a), and a spiral channel (101c) extending spirally along an extending direction of the air inlet channel (101b); The spiral channel (101c) is improved from a flat-top type to a spiral channel (101c) with one spiral turn, and the angle of the air inlet channel (101b) is changed from a horizontal entry angle to the same angle as the air inlet (101a), i.e., an entry angle of 26°; The separation assembly (102) comprises a cylindrical separation chamber (102a) fixedly connected to the outer wall of the spiral channel (101c), and an inverted cone separation chamber (102b) fixedly connected to the bottom of the cylindrical separation chamber (102a); The ratios of the cavity height of the cylindrical separation cavity (102a) and the inverted cone separation cavity (102b) to the diameter of the cylindrical separation cavity (102a) are both increased to 4; The exhaust component (201) comprises an exhaust channel (201a) arranged inside the columnar separation chamber (102a), and an exhaust port (201b) arranged on one side of the exhaust channel (201a); The ratio of the diameter of the exhaust channel (201a) to the diameter of the cylindrical separation chamber (102a) is reduced to 0.54, and the ratio of the diameter of the exhaust port (201b) to the diameter of the cylindrical separation chamber (102a) is reduced to 0.42; The dust exhaust component (202) comprises a dust exhaust port (202a) arranged at the bottom of the inverted cone-shaped separation chamber (102b), and a dust collection channel (202b) fixedly connected to the dust exhaust port (202a); The ratio of the diameter of the dust exhaust port (202a) to the diameter of the cylindrical separation chamber (102a) is reduced to 0.

37.

2. A pulverized coal separation system, characterized in that: comprising the cyclone separator according to claim 1; and A separation system (M) comprises a coarse separation module (300) connected to the air inlet unit (100), a grinding module (400) connected to the coarse separation module (300), a feeding module (500) connected to the grinding module (400), a combustion module (600) connected to the discharge unit (200), and a dust collection module (700) connected to the dust exhaust unit.

3. The pulverized coal separation system according to claim 2, characterized in that: The separation system (M) further comprises an adjustment module (800) connected to the air inlet unit (100), and a control module (900) connected to the adjustment module (800).

4. The pulverized coal separation system according to claim 3, characterized in that: The coarse classification module (300) includes a coarse powder separator (301); the grinding module (400) includes a ball mill (401); the feeding module (500) includes a feeding hopper (501); the combustion module (600) includes a boiler furnace (601); the dust collection module (700) includes a coal ash bucket (701); the regulating module (800) includes a regulating valve (801); and the control module (900) includes a control terminal (901).

5. The pulverized coal separation system according to claim 4, characterized in that: The regulating modules (800) are respectively arranged at both ends of the inlet and outlet of the cyclone separator and at the outlet of the feed module (500) to adaptively regulate the feed flow rate, the discharge speed of dust particles and the discharge speed of residual gas, and floating flow meters are respectively arranged at the inlet of the coarse separation module (300) and the cyclone separator to monitor the incoming flow rate in real time.

6. A method for optimizing the structure of a cyclone separator, characterized in that: The flow field distribution inside the separator is analyzed through the coupling model of fluid mechanics and discrete phase, the trajectory of dust particles is predicted, and the inlet and outlet pressure drops and separation efficiency are calculated; The exhaust pipe diameter, dust outlet diameter, cone height, exhaust pipe insertion depth and inlet velocity are taken as design variables, and dimensionless according to the cylinder diameter. The separation efficiency and total pressure drop are taken as response targets, and a second-order polynomial response surface model is established, which is used as the fitness function of the genetic algorithm. The genetic algorithm toolbox of Matlab software is used to solve the fitness function of separation efficiency and total pressure drop. Taking maximum efficiency and minimum pressure drop as the goals, a series of optimal solution sets are obtained under the common constraints of five design variables.

7. The method for optimizing the structure of a cyclone separator according to claim 6, characterized in that: The coupling model includes: The RSM turbulence model was selected to simulate the complex flow field inside the cyclone separator; According to the model constants σk, C1, C2, the RSM turbulence model is used to simulate the flow field inside the cyclone separator. The gas phase fluid velocity is represented by u. The gas phase flow field inside the cyclone separator is calculated by the following formula, where the constants are usually taken as σk = 1, C1 = 1.8, C2 = 0.6; Among them, P and Vt in the above formula represent turbulent kinetic energy and kinematic viscosity respectively, and the upper and lower eddy currents in the separator are described by Pij, and the constant Cu is taken as 0.

9. The values ​​of P, Vt and Pij are as follows:

8. The method for optimizing the structure of a cyclone separator according to claim 7, characterized in that: The RSM turbulence model also includes, The calculation formula of the gas phase flow field inside the cyclone separator is as follows: ε represents the turbulent dissipation rate, K represents the measure of the development of turbulent motion in the separator, and the constants ε = 1.3, Cε1 = 1.44, Cε2 = 1.92, where ε and K are calculated according to the following equations: In the above formula, Rij represents the Reynolds shear stress and xi is the position vector; according to the calculated quantity, u' represents the fluid fluctuation velocity, is the average flow velocity; ρ is the gas phase fluid density, is the time-averaged pressure, ui and uj are the components of the fluid velocity, which are used to calculate Rij to close the Reynolds-averaged Navier-Stokes equation, which is as follows:

9. The method for optimizing the structure of a cyclone separator according to claim 8, characterized in that: The second-order polynomial response surface model includes, The obtained response values ​​were fitted with the simulated data using statistical and mathematical methods based on the least squares method to obtain the following multivariate quadratic regression equation: Among them, Yn is the response variable, n=1 represents pressure drop, n=2 represents separation efficiency; b0, bi, bij, bii are intercept, linear coefficient, interaction coefficient, quadratic term coefficient respectively; xi, xj are design variables respectively, i, j=1, 2, 3, 4, 5, corresponding to the five main structural parameters of the separator to be studied: exhaust pipe diameter, dust outlet diameter, cone height, exhaust pipe insertion depth and inlet velocity.

10. The cyclone separator structure optimization method according to claim 9, characterized in that: The Matlab software genetic algorithm includes, With the maximum efficiency and minimum pressure drop as the goal, a series of optimal solution sets are obtained under the common constraints of the five design variables. The calculation method is as follows: Among them, the constraints of the fitness function and the five design variables are as follows: Minimum voltage drop Y1(x1,x2,x3,x4,x5) Maximum efficiency Y2(x1,x2,x3,x4,x5) Constraint (0.4 <x1<0.6) (0.2<x2<0.4) (2<x3<4) (0.5<x4<1.5) (12<x5<20) The optimal solution set calculated under the above conditions, each solution corresponds to a combination of design parameters.

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