Method for greatly improving self-cleaning effect of filter element of air filter and testing device

Abstract

The invention relates to the technical field of air filter cleaning, in particular to a method for greatly improving the self-cleaning effect of a filter element of an air filter and a testing device. Comprising an air filter element, a filter element fixing nut, a filter element fixing support, a newly-added baffle fixing support, a newly-added baffle fixing bolt, a newly-added baffle, a Venturi tube, a pulse valve, a pulse signal generator, an energy accumulator, a baffle mandrel and eight movable air baffles, and the air filter element is fixed to the filter element fixing support through the filter element fixing nut; the newly-added baffle fixing support is arranged in the air filter element, and the newly-added baffle is installed on the newly-added baffle fixing support through newly-added baffle fixing bolts. And the Venturi tube is arranged on the filter element of the air filter, so that the technical problem that in the prior art, when the filter element of the air filter is cleaned, only one half part is backwashed, and the other half part cannot be backwashed, so that the cleaning effect is influenced is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of air filter cleaning, and in particular to a method and a testing device for greatly improving the self-cleaning effect of an air filter element. Background Art

[0002] In cement plants, flour mills and other material processing enterprises, there are a large number of materials flying in the air that need to be recovered. There has long been a bag-type pulse recovery device. It uses dozens or even hundreds of bags installed at the inlet of the induced draft fan to intercept materials such as cement or flour suspended in the air. Through time or pressure difference control, a set of electromagnetic pulse valves are controlled by a timing pulse controller, and 0.6-0.8MPa compressed air is used to perform pulse backwashing on the filter bags, so that the recovered materials are shaken into the container and the materials are recovered. Based on this idea, there are many existing pulse self-cleaning air filters. The working principle is as follows: Figure 1 As shown, this "dynamic" air filter has obvious technical advantages over the "static" air filter, so it was soon widely used in many occasions requiring air purification, such as gas turbines, large air compressors, factory ventilation, etc.

[0003] However, the pulse self-cleaning air filter is different from the bag-type material recovery device: the latter mainly relies on the vibration of the pulse airflow to shake the material off the bag, and then relies on the pulse airflow to blow the shaken-off material away and let it fall freely; the filter material of the pulse self-cleaning air filter element must have a very high filtration accuracy and high air permeability, as well as a high burst resistance, otherwise the filtration accuracy will decrease after several strong pulse backwashings, which is not allowed. It is generally a rigid barrel structure; furthermore, the air flow field changes of the pulse self-cleaning air filter air backwashing are very complicated, which results in the backwashing effect of the existing pulse self-cleaning air filter not being completely as good as expected. Figure 1 As shown, when the air filter element is cleaned, only half of it is backwashed, and the other half is not backwashed, which affects the cleaning effect. Summary of the invention

[0004] The purpose of the present invention is to provide a method and a testing device that greatly improves the self-cleaning effect of an air filter element, aiming to solve the technical problem in the prior art that when cleaning an air filter element, only half of the element is backwashed, while the other half is not backwashed, thus affecting the cleaning effect.

[0005] To achieve the above-mentioned purpose, the present invention adopts a test device for greatly improving the self-cleaning effect of an air filter element, comprising an air filter element, a filter element fixing nut, a filter element fixing bracket, a newly added baffle fixing bracket, a newly added baffle fixing bolt, a newly added baffle, a venturi tube, a pulse valve, a pulse signal generator, an accumulator, a baffle core shaft, and eight movable air baffles, wherein the air filter element is fixed to the filter element fixing bracket by the filter element fixing nut, the newly added baffle fixing bracket is arranged in the air filter element, the newly added baffle is installed on the newly added baffle fixing bracket by the newly added baffle fixing bolt, the baffle core shaft is parallel to the central axis of the filter element, the eight movable air baffles swing with the gap between the baffle core shaft, and the eight movable air baffles are consistent in area, mass, wall thickness, and material;

[0006] The venturi tube is arranged on the air filter element, the accumulator is connected to an external air source, the pulse valve is connected to the accumulator, and the pulse signal generator is connected to the pulse valve.

[0007] The present invention also provides a method for significantly improving the self-cleaning effect of an air filter element, which is applied to the test device for significantly improving the self-cleaning effect of an air filter element as described above.

[0008] The following steps are involved:

[0009] Without installing the newly added baffle, supply the accumulator with 0.6-0.8MPa compressed air, power on the pulse signal generator, output pulse signals of T1=80-120ms and T2=10-15s, and the pulse valve (8) is opened / closed synchronously according to the T1 / T2 signal. If the pulse valve is heard to spray high-speed compressed air into the Venturi tube at an interval of T2, it is felt that the pulse valve's jet airflow draws a large amount of air into the Venturi tube with considerable kinetic energy E0, indicating that installing the Venturi tube can enhance the effect of pulse backwashing. Among them, during the pulse backwashing process, it was found that only the movable air deflector far away from the inlet of the air filter element swung outward at a certain angle θ, and the closer to the bottom of the air filter element, the larger the swing angle θ of the movable air deflector from 4# to 1#, indicating that there were different backwashing effects from small to large; on the contrary, the closer to the inlet of the filter element, the movable air deflector from 5# to 8# not only did not swing outward, but also swung inward, and the angle θ was larger; the air filter element in this section had an obvious inward suction phenomenon, which can be observed that within the total length L0, 1 / 2 of the air filter element has no backwashing cleaning effect at all.

[0010] Among them, prepare multiple pieces from small to large The newly added baffles of different sizes were tested and compared from small to large. The above test was repeated and it was found that After the baffle of the size is added, the swing angle θ of the movable air baffle away from the air filter element changes significantly, that is, the swing angle θ of the movable air baffle from 4# to 1# is getting smaller, and at the same time, the inward swing angle θ of the movable air baffle from 5# to 8# is also changing, and the change is also getting smaller; when the test reaches the corresponding When adding the baffle of the same size, it is found that the swing angle θ of the movable wind baffle from 8# to 1# gradually changes little; The size of the newly added baffle is increased or decreased, and the above test is repeated to make the swing angle θ of the movable wind baffles from 8# to 1# basically consistent.

[0011] Among them, in the determined After adding the baffle of the same size, one or two gaskets of different thicknesses are added before and after the fixing bracket of the new baffle, that is, the L is adjusted. X The distance between the movable air baffles 8# and 1# makes the swing angle θ of the movable air baffles 8# and 1# tend to be consistent; so far, for the corresponding length L0 of the air filter element and the pulse backwashing device, the outer diameter D of the filter element, the inner diameter d of the filter element, the filter paper model, the number of folds N of the filter paper, the air supply pressure P1, the pulse parameters T1 and T2 remain unchanged, the geometric dimensions and L2 of the Venturi tube are determined, and the newly added baffle Dimensions and distance L for installing the additional baffle X That is, it can be determined that at this time, the air filter element is evenly pulse-backwashed within the entire length L0.

[0012] The present invention provides a method and a testing device for greatly improving the self-cleaning effect of an air filter element. The method determines the diameter and installation position of the newly added baffle plate according to the testing device for greatly improving the self-cleaning effect of an air filter element. Then, the newly added baffle plate fixing bracket is fixed at the specified position of the axis of the air filter element, and the newly added baffle plate is installed on the newly added baffle plate fixing bracket through the newly added baffle plate fixing bolt. An external air source supplies air to the venturi tube, and the gas backwashes the air filter element. In this way, the technical problem in the prior art that only half of the air filter element is backwashed when cleaning, while the other half is not backwashed, thereby affecting the cleaning effect is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 paying creative work.

[0014] Figure 1It is a schematic diagram of the working principle of an existing pulse self-cleaning air filter.

[0015] Figure 2 It is a structural schematic diagram of a testing device for greatly improving the self-cleaning effect of an air filter element of the present invention.

[0016] 1-air filter element, 2-filter element fixing nut, 3-filter element fixing bracket, 4-new baffle fixing bracket, 5-new baffle fixing bolt, 6-new baffle, 7-venturi tube, 8-pulse valve, 9-pulse signal generator, 10-accumulator, 11-baffle core shaft, 12-movable wind baffle, P1-compressed air pressure, P2-nozzle outlet pressure, Px-corresponding Ex wind pressure, T1-pulse width, T2-pulse period, ta-compressed air temperature, C1-nozzle outlet air velocity, Cx-corresponding Ex wind speed, m1-injection flow rate, m2-venturi tube induced air flow rate, △P-venturi tube drainage pressure difference, E0-total kinetic energy of backblowing air, Ex-kinetic energy of air filter element after installing the baffle, d-inner diameter of air filter element, D-outer diameter of air filter element, Фx-diameter of intercepting baffle, L0-total length of air filter element, L1-height of venturi tube, L2-distance between venturi tube and nozzle, L3-width of wind shield, L4-length of wind shield, Lx-distance between intercepting baffle and air filter element, 0-blowing angle of wind shield. DETAILED DESCRIPTION

[0017] Embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0018] See also Figure 1 and Figure 2 ,in Figure 1 This is a schematic diagram of the working principle of the existing pulse self-cleaning air filter. Figure 2 It is a structural schematic diagram of a testing device for greatly improving the self-cleaning effect of an air filter element of the present invention.

[0019] The present invention provides a testing device which can greatly improve the self-cleaning effect of an air filter element.

[0020] It includes an air filter element 1, a filter element fixing nut 2, a filter element fixing bracket 3, a newly added baffle fixing bracket 4, a newly added baffle fixing bolt 5, a newly added baffle 6, a venturi tube 7, a pulse valve 8, a pulse signal generator 9, an accumulator 10, a baffle core shaft 11, and eight movable air baffles 12. The air filter element 1 is fixed to the filter element fixing bracket 3 through the filter element fixing nut 2, the newly added baffle fixing bracket 4 is arranged in the air filter element 1, the newly added baffle 6 is installed on the newly added baffle fixing bracket 4 through the newly added baffle fixing bolt 5, the baffle core shaft 11 is parallel to the central axis of the filter element, the eight movable air baffles 12 swing with the baffle core shaft 11, and the eight movable air baffles 12 are consistent in area, mass, wall thickness, and material;

[0021] The venturi tube 7 is arranged on the air filter element 1 , the accumulator 10 is connected to an external air source, the pulse valve 8 is connected to the accumulator 10 , and the pulse signal generator 9 is connected to the pulse valve 8 .

[0022] The present invention also provides a method for significantly improving the self-cleaning effect of an air filter element, which is applied to the test device for significantly improving the self-cleaning effect of an air filter element as described above.

[0023] The following steps are involved:

[0024] In order to facilitate quantitative calculation and qualitative analysis, a commonly used standard filter element can be used for testing, that is, d = 212mm, D = 325mm, L0 = 665mm, N = 280 folds, flow rate q = 18m 3 / min, initial pressure drop 200Pa; P1 = 0.7MPa (absolute), pulse valve 8 outlet P2 = 0.2MPa (absolute); T1 = 0.1S, T2 = 15S; L1 = 350mm, L2 = 50mm, L3 = 75mm, L4 = 500mm, aluminum, thickness 1mm; L X =100mm, 6 types: 45mm, 50mm, 55mm, 60mm, 65mm.

[0025] According to ISO working conditions, that is Air density p0 = 1.22 kg / m 3 .

[0026] Since P2 / P1=0.2 / 0.7=0.2857<0.528 (critical pressure ratio), the air flow rate C1 at the outlet of the pulse valve 8 (8) is calculated according to the Laval nozzle formula:

[0027] C1=[2g(k / k-1)*R*T*(1-(P2 / P1) K-1 / K ]Λ2(m / s)

[0028] Set g = 9.8 m / s 2 , k = 1.4, R = 29.3kg.m / kg.k, T = 273 + 15, P1 = 0.7MPa, P2 = 0.2MPa Substituting into the above formula, we get

[0029] C1=417.7m / s, which is supersonic.

[0030] Since the outlet pressure P2 = 0.2MPa, which is twice as high as the free state P0, the outlet p1 of the pulse valve 8 is 2.44kg / m 3 ,

[0031] According to Pascal's formula, the pressure difference at the inlet of the Venturi tube 7 is ΔP=0.5*p1*C1 2 (Pa)

[0032] =0.5*2.44*417.7 2 =212830Pa=0.213KPa<0.1MPa,

[0033] Therefore, a siphon effect is generated, and air with a mass of m2 is sucked into the venturi tube 7. The mass of m2 is generally 3 to 4 times the mass m1 ejected at the outlet of the pulse valve 8, and the total mass m0 = m1 + m2.

[0034] According to the engineering experience of many pulse self-cleaning air filter manufacturers over the years, Figure 1 The compressed air consumption during pulse backwashing of the filter element shown is about 50l / min. Since the siphon effect consumes part of the kinetic energy, the speed of the pulse air flow entering the air filter is slightly greater than the local sound speed of 350m / s.

[0035] According to the fluid mechanics Palauli equation, the total energy of the pulse air flow entering the air filter is

[0036] E0=EX1+E X2 +E X3 +E X4 +E X5 +E X6 +E X7 +E X8 =ΣE X

[0037] E X =m0*(P X +0.5*px*C X 2 *L0).

[0038] Where P X It is the pressure in high-speed flowing air, which can be converted into expansion work; expansion work

[0039] W=m0*(k / k-1)*R*T*[1-(P X / P1) K-1 / K ](J)

[0040] P X = 0 when the expansion work is the largest, P X =P X The expansion work is zero.

[0041] If the air filter element 1 is a closed pipe, the kinetic energy is 0.5*pxC X 2 Equal everywhere, but L0 is very short, 0.5*px*C X 2 *L0 can be ignored. Finally, the total energy is converted from the potential energy of P1 to kinetic energy at the bottom of the air filter element 1. The kinetic energy is the largest, and the reverse airflow is offset by C1 and scattered around.

[0042] Now the air filter element 1 is a round barrel with air permeability on all sides, and the flow rate at the inlet of the air filter element 1 is about C8 = 360m / s. According to Pascal's formula, there is a negative pressure ΔP = 0.5*2.44*360 near the inlet of the air filter element 1. 2 =158112Pa, and air is sucked into the air filter element 1; as the air outside the air filter element 1 continues to enter, C X 、p X and P X The pulse time is very short, that is, 0.1S. When the airflow reaches the bottom of the air filter element 1, P1 is slightly smaller than the original P1. Most of the pressure energy is still converted into kinetic energy. When the airflow reaches the bottom of the air filter element 1, P X =0, there is a reverse airflow greater than C1 to the outside of the air filter element 1 to backwash the dust accumulated in the air filter element 1, so only a part of the air filter element 1 is pulse backwashed.

[0043] In order to improve this abnormal state, we can install a new baffle with a suitable outer diameter at a certain position on the axis of the air filter element 1 to reduce the pressure of a small part of the air flow to zero in advance, so that this part of the pressure can be converted into kinetic energy, so that C X ,>C X >250000Pa or so, but it does not affect E too much X1 ~E X6 or E X7 Pulse backwashing of parts.

[0044] Since the actual air permeability of the filter element cannot be accurately calculated, the diameter of the additional baffle can only be determined through a test device. and installation position L X .

[0045] The first step is not to install the newly added baffle 6. Supply 0.6-0.8MPa compressed air to the accumulator 10, power on the pulse signal generator 9, and output pulse signals of T1=80-120ms (adjustable) and T2=10-15s (adjustable). The pulse valve 8 is synchronously opened / closed according to the T1 / T2 signal. Not only can you hear the pulse valve 8 spraying high-speed compressed air to the venturi tube 7 at intervals, but you can also feel by hand or other methods that the jet airflow of the pulse valve 8 draws a large amount of air to the venturi tube 7, which has considerable kinetic energy E0, indicating that installing the venturi tube 7 can enhance the effect of pulse backwashing.

[0046] Further, prepare 6 different The newly added baffles 6 of different sizes were tested for installation from small to large. The above test was repeated, and it was found that after the newly added baffles 6 were installed, the swing angle θ of the movable air baffle 12 away from the air filter element 1 changed significantly, that is, the swing angle θ of the movable air baffles 12 from 4# to 1# was decreasing, and at the same time, the inward swing angle θ of the movable air baffles 12 from 5# to 8# was also changing, and the change of θ was also decreasing; when the test reached a certain When the baffle 6 of the size is added, it is found that the swing angle θ of the movable wind baffle 12 from 8# to 1# gradually changes little; The size of the newly added baffle 6 is appropriately increased or decreased, and the above test is repeated to make the swing angle θ of the movable wind baffles 12 from 8# to 1# basically consistent.

[0047] Next, in the determined On the basis of the newly added baffle 6 of the size, one or two gaskets of different thickness are added before and after the newly added baffle fixing bracket, that is, the L is adjusted. X The distance between the movable wind shield plates 12 from 8# to 1# makes the swing angle θ more consistent.

[0048] At this point, for a certain model of the air filter element 1 and the pulse backwashing device (i.e., the length L0, D, d, filter paper model, analysis number N, air supply pressure P1, T1, T2 remain unchanged, and the geometric dimensions and L2 of the venturi tube 7 are determined), the size of the newly added baffle 6 and the distance L for installing the newly added baffle 6 are X That can be determined.

[0049] The pulse self-cleaning air filter designed or modified according to the present invention has achieved a very significant pulse self-cleaning effect. Currently, there are nearly a thousand gas turbines in use, and thousands of gas turbines are in use all over the world. They are all equipped with pulse self-cleaning air filters. Some units are equipped with 700 to 800 sets of straight barrel + cone pulse self-cleaning air filters. Generally, a set of air filters is replaced every 3000 to 3500 hours, and each set of air filters costs 1500 to 3000 yuan. If these ordinary air filters are designed or modified according to the present invention, it can save hundreds of millions of yuan in production costs for gas turbine users every year, which has significant economic benefits.

[0050] A method and a test device for significantly improving the self-cleaning effect of an air filter element are used in accordance with the present embodiment. The diameter and installation position of the newly added baffle 6 are determined according to the test device for significantly improving the self-cleaning effect of an air filter element. Then, the newly added baffle fixing bracket 4 is fixed at the specified position of the axis of the air filter element 1, and the newly added baffle 6 is installed on the baffle fixing bracket 4 through the newly added baffle fixing bolt 5. An external air source supplies air to the venturi tube 7, and the gas backwashes the air filter element 1. In this way, the technical problem in the prior art that only half of the air filter element 1 is backwashed when being cleaned, while the other half is not backwashed, thus affecting the cleaning effect is solved.

[0051] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A test device for greatly improving the self-cleaning effect of an air filter element, characterized in that: The invention comprises an air filter element (1), an element fixing nut (2), an element fixing bracket (3), a newly added baffle fixing bracket (4), a newly added baffle fixing bolt (5), a newly added baffle (6), a venturi tube (7), a pulse valve (8), a pulse signal generator (9), an accumulator (10), a baffle core shaft (11), and eight movable air baffles (12); the air filter element (1) is fixed to the element fixing bracket (3) by the element fixing nut (2); the newly added baffle fixing bracket (4) is arranged in the air filter element (1); the newly added baffle (6) is installed on the newly added baffle fixing bracket (4) by the newly added baffle fixing bolt (5); the baffle core shaft (11) is parallel to the central axis of the filter element; the eight movable air baffles (12) swing with the baffle core shaft (11); and the eight movable air baffles (12) are consistent in area, mass, wall thickness, and material; The venturi tube is arranged on the air filter element (1), the accumulator (10) is connected to an external air source, the pulse valve (8) is connected to the accumulator (10), and the pulse signal generator (9) is connected to the pulse valve (8).

2. A method for significantly improving the self-cleaning effect of an air filter element, applied to the test device for significantly improving the self-cleaning effect of an air filter element as claimed in claim 1, characterized in that: The following steps are involved: Without installing the newly added baffle (6) first, supply the accumulator (10) with compressed air of 0.6-0.8 MPa, power on the pulse signal generator (9), output pulse signals of T1=80-120 ms and T2=10-15 s, and the pulse valve (8) is opened / closed synchronously according to the T1 / T2 signal. If the pulse valve (8) is heard to spray high-speed compressed air into the Venturi tube (7) at an interval of T2, and if the pulse valve (8) is felt to eject a large amount of air into the Venturi tube (7) with considerable kinetic energy E0, it indicates that installing the Venturi tube (7) can enhance the effect of pulse backwashing.

3. The method for significantly improving the self-cleaning effect of an air filter element according to claim 2, characterized in that: During the pulse backwashing process, it was found that only the movable air deflector (12) far from the inlet of the air filter element (1) swung outward at a certain angle θ. The closer to the bottom of the air filter element (1), the larger the swing angle θ of the movable air deflector (12) from 4# to 1#, indicating that there were different backwashing effects from small to large. On the contrary, the closer to the inlet of the filter element, the movable air deflector (12) from 5# to 8# not only did not swing outward, but also swung inward, and the angle θ was larger. The air filter element (1) in this section had an obvious inward suction phenomenon, and it can be observed that within the total length L0, there is a 1 / 2 part of the air filter element (1) that has no backwashing cleaning effect at all.

4. The method for significantly improving the self-cleaning effect of an air filter element according to claim 3, characterized in that: Prepare multiple pieces from small to large The newly added baffle (6) of the size was tested and compared from small to large; the above test was repeated and it was found that After the baffle (6) of the size is added, the swing angle θ of the movable air shield (12) away from the air filter element (1) changes significantly, that is, the swing angle θ of the movable air shield (12) from 4# to 1# is decreasing, and at the same time, the inward swing angle θ of the movable air shield (12) from 5# to 8# is also changing, and the change of θ is also decreasing; when the test reaches the corresponding When the additional baffle (6) of the size is added, it is found that the swing angle θ of the movable wind baffle (12) from 8# to 1# gradually changes little; The size of the newly added baffle (6) is increased or decreased, and the above test is repeated, so that the swing angle θ of the movable wind baffles (12) from 8# to 1# is basically consistent.

5. The method for significantly improving the self-cleaning effect of an air filter element according to claim 4, characterized in that: In the determined After the newly added baffle (6) of the same size is installed, one or two gaskets of different thicknesses are added before and after the newly added baffle fixing bracket, that is, L is adjusted. X The distance between the movable air baffles (12) from 8# to 1# is such that the swing angle θ of the movable air baffles (12) is close to the same; thus, for the corresponding length L0 of the air filter element (1) and the pulse backwashing device, the outer diameter D of the filter element, the inner diameter d of the filter element, the filter paper model, the number of folds N of the filter paper, the air supply pressure P1, the pulse parameters T1 and T2 remain unchanged, the geometric dimensions and L2 of the Venturi tube (7) are determined, and the newly added baffle (6) is Size and distance L for installing the newly added baffle (6) X That is, it can be determined that at this time, the air filter element (1) is evenly pulse-backwashed within the entire length L0.

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