CN111821793A

CN111821793A - Method for improving filtering performance of dry paint spray booth

Info

Publication number: CN111821793A
Application number: CN202010576922.2A
Authority: CN
Inventors: 高维龙; 陈小邦; 刘洪赐; 明海; 宋社伟
Original assignee: Dongfeng Motor Co Ltd
Current assignee: Dongfeng Motor Co Ltd
Priority date: 2020-06-22
Filing date: 2020-06-22
Publication date: 2020-10-27
Anticipated expiration: 2040-06-22
Also published as: CN111821793B

Abstract

The invention provides a method for improving the filtering performance of a dry paint spray booth, which comprises the steps of forming airflow to be filtered containing paint particles, which directionally flows from a paint spray booth to a windward port of a filtering chamber, by means of pressure difference between the paint spray booth and the filtering chamber; providing an adsorption structure arranged in the flowing direction of the airflow to be filtered, and filtering in a first stage; providing a nozzle capable of spraying powder, wherein the nozzle sprays the powder to perform second-stage filtration; powder sprayed from the nozzle is settled on a containing structure with a plurality of through holes by gravity, a vibrator capable of driving the containing structure to vibrate is provided, and the powder accumulated on the containing structure is discharged through the through holes under the action of the vibrator; the filter is provided to carry out the third stage of isolation filtration, and clean air is obtained and discharged from the air outlet of the filter chamber. The invention improves the filtering performance of the dry paint spray booth by reducing the agglomeration and blockage of powder and paint.

Description

Method for improving filtering performance of dry paint spray booth

Technical Field

The invention belongs to the technical field of paint mist filtering, and particularly relates to a method for improving filtering performance of a dry paint spray booth by reducing agglomeration and blockage of lime powder and paint.

Background

The paint spray booths are classified according to the paint mist trapping mode and can be divided into a wet paint spray booth and a dry paint spray booth; the wet paint spray booth may be classified into a venturi type, a water-rotating type (power tube type), a water curtain type, etc. which capture paint mist with water, and the dry paint spray booth may be classified into a conventional filter-cotton dry paint spray booth, a lime powder dry paint spray booth, and a novel dry carton type paint spray booth. In the current automobile coating industry, 2K varnish is widely popularized and utilized due to good performance, but the 2K varnish is easy to cure due to high viscosity, and challenges are brought to a dry type spray booth technology for capturing paint mist by using lime powder.

The main existing problems are:

1. the service life of the filter is short-the paint mist is solidified on the surface of the filter and is firmly adhered;

2. the lime powder is used in a large amount;

3. 2K varnish paint mist is solidified and agglomerated in a dry type spray booth filtering system, the cleaning difficulty is high, and the maintenance cost is high;

4. lime powder agglomerates, the equipment failure rate is high, and the production efficiency is influenced by long-time shutdown.

The application provides a method for improving the filtering performance of a dry paint spray booth by reducing the caking and blocking phenomena of lime powder and paint aiming at the improvement of a lime powder dry paint spray booth adopted by an automobile coating workshop.

Disclosure of Invention

In response to the deficiencies of the prior art, the present invention provides a method for improving the filtration performance of dry paint spray booths by reducing the caking and clogging of powders and paint.

In order to achieve the above objects, the present invention provides a method of improving the filtration performance of a dry spray booth for filtering paint particles produced by the spray booth in the dry spray booth, the method comprising:

forming a to-be-filtered airflow containing paint particles which directionally flows from the paint spraying chamber to a windward opening of the filtering chamber by the pressure difference between the paint spraying chamber and the filtering chamber;

providing an adsorption structure arranged in the flowing direction of the air flow to be filtered, and filtering paint particles contained in the air flow to be filtered in a first stage;

providing a nozzle capable of spraying powder, wherein the nozzle sprays the powder towards the airflow to be filtered in a set direction, and paint particles contained in the airflow to be filtered are filtered in a second stage;

the powder sprayed from the nozzle is settled on a containing structure with a plurality of through holes by gravity, a vibrator capable of driving the containing structure to vibrate is provided, and the powder accumulated on the containing structure is discharged through the through holes under the action of the vibrator;

the filter is provided to carry out a third stage of isolated filtration of the paint particles contained in the air flow to be filtered, obtaining clean air and discharging the clean air from the air outlet of the filter chamber.

According to another embodiment of the invention, a purging structure capable of extending into a surface of an inner filter element of a filter is provided, the purging structure capable of creating a purging airflow towards the surface of the inner filter element of the filter, the purging airflow cleaning a dust accumulation on the surface of the inner filter element of the filter.

According to another embodiment of the invention, the first stage of filtration is in the form of contact filtration, the adsorption structure providing an air inlet, an air outlet, at least one adsorption baffle for direct contact with the air flow to be filtered containing paint particles, wherein a non-horizontal flow path is formed between the air inlet and the air outlet, and the air flow flowing into the adsorption structure from the air inlet changes its direction of flow after encountering the adsorption baffle and flows out from the air outlet.

The non-horizontal flow passage is characterized in that in the process of flowing of air flow between the air inlet and the air outlet, at least the direction of the air flow is changed in the horizontal direction and/or the vertical direction, so that the air flow to be filtered containing paint particles can directly impact the adsorption baffle, and part of paint mist is solidified and gathered on the surface of the adsorption baffle, so that the paint particles are filtered.

According to another embodiment of the present invention, a plurality of adsorption baffles are provided, and adjacent adsorption baffles are staggered to form a wave-shaped labyrinth flow passage between the adsorption baffles.

According to another embodiment of the present invention, a plurality of adsorption baffles are provided, each adsorption baffle is provided with a plurality of directional holes for the air flow to pass through, and the corresponding directional holes of adjacent adsorption baffles are staggered.

According to another embodiment of the invention, a membrane is provided that can be attached to an adsorption barrier, the membrane being adapted to adsorb paint particles, and the membrane being removable from the adsorption barrier (52) to facilitate a cleaning operation.

The film structure is convenient for cleaning paint slag adhered to the surface of the adsorption baffle, the existing painting industry workshop mostly adopts 2K varnish paint, the 2K varnish is easy to solidify into paint skin when meeting air, and the paint skin is very difficult to clean, so that the film structure only needs to be replaced when the paint slag on the adsorption baffle is cleaned.

Preferably, the film structure is a bonded flame retardant film.

According to another embodiment of the invention, the powder sprayed out of the nozzle falls from above downwards and forms a curtain through which the air flow to be filtered containing paint particles flows in a horizontal direction towards the windward opening of the filter.

According to another embodiment of the present invention, the nozzle sprays the dust upward at an angle of inclination R1 until the dust impinges on a divider plate for distributing the dust sufficiently that the powder falls gravitationally to form a curtain of adsorbed paint particles.

Wherein the inclination angle R1 is preferably 30-60 deg..

Specifically, the powder with better adsorption performance has certain speed after being sprayed out from the nozzle, and the powder under high speed impacts on the partition plate to disperse the powder to the periphery to form dispersed lime powder mist with smaller granularity, so that paint particles in airflow to be filtered are better wrapped and adsorbed.

According to another embodiment of the present invention, the housing structure provides:

an inclined intake plate, the angle of inclination R2 between the intake plate and the direction of flow of the air flow to be filtered being set to be less than 45 DEG, wherein a plurality of through holes are distributed on the intake plate;

the inclined drainage plate is positioned below the containing plate, and the powder on the containing plate passes through the through holes and is collected under the drainage of the drainage plate;

wherein, the inclination angle R2 between the receiving plate and the flowing direction of the airflow to be filtered is set to be less than 45 degrees, the inclination angle between the flow guiding plate and the flowing direction of the airflow to be filtered is R3, and R3 is more than or equal to R2.

According to another embodiment of the present invention, a mixing chamber, a grid, is provided, and the powder collected on the flow guide plate falls into the mixing chamber after passing through the grid.

According to another embodiment of the present invention, a measuring device disposed at the air outlet of the adsorption structure is provided, and the measuring device detects the airflow flow at the air outlet of the adsorption structure to control the spraying speed of the nozzle in a chain manner.

According to another embodiment of the invention, the lime powder spraying process can be interlocked with a paint spraying robot in a paint spraying chamber, and the lime powder spraying process can be adjusted by receiving signals of the paint spraying robot.

The invention has the following beneficial effects:

according to the method for improving the filtering performance of the dry paint spray booth, paint particles in gas to be filtered are filtered in a multi-stage filtering mode, a special adsorption structure is arranged to adsorb the gas to be filtered in a contact mode, and part of paint mist is solidified and gathered on the surface of an adsorption baffle, so that the load of a subsequent filtering process can be greatly reduced.

In addition, the invention sets a more reasonable spraying angle, and can quickly collect the powder used by spraying so as to carry out subsequent recycling and reduce the dosage of the powder.

In addition, the containing structure for collecting the sprayed powder provides a vibration mode, the containing structure is driven to shake according to a set frequency, the powder and paint mist falling on the surface of the containing structure are dispersed in a vibration mode and then discharged from the through hole, the phenomenon of agglomeration of the powder and the paint mist is eliminated, and loss caused by shutdown maintenance due to blockage of the nozzle is greatly reduced.

In addition, the film structure is arranged on the adsorption baffle plate, so that the solidified paint skin on the adsorption baffle plate can be conveniently cleaned, and the cleaning process is more convenient and faster.

In addition, the surface of the filter element of the filter playing a main role is swept by the sweeping structure, so that paint mist and powder agglomeration on the surface of the filter element of the filter are eliminated, the phenomenon of lime powder blockage is obviously reduced, the service life of the filter element of the filter is prolonged, and the equipment failure rate is greatly reduced

The present invention will be described in further detail with reference to the accompanying drawings.

Drawings

FIG. 1 is a schematic flow diagram of the method of improving filtration performance of a dry spray booth of the present invention;

FIG. 2 is a schematic structural view of a dry spray booth for carrying out the method of the present invention;

FIG. 3 is a schematic view of the structure of the spraying device of FIG. 2;

FIG. 4 is a schematic view of a specific structure of the pre-adsorption apparatus shown in FIG. 2;

FIG. 5 is a schematic view of another embodiment of the pre-adsorption apparatus of FIG. 2;

fig. 6 is an enlarged schematic view of the purge device of fig. 2.

Detailed Description

A method of improving the filtration performance of a dry spray booth, as shown in fig. 1, for filtering paint particles produced by a spray booth in the dry spray booth, the method comprising:

generating directional flow airflow: arranging a circulating fan, forming a negative pressure area at the air inlet 21 of the filter chamber 20, namely forming a pressure difference between the paint spraying chamber 10 and the filter chamber 20, and forming a to-be-filtered air flow containing paint particles which directionally flows from the paint spraying chamber 10 to the air inlet 21 of the filter chamber 20;

filtration in the first stage: providing an adsorption structure 50 arranged in the flow direction of the gas flow to be filtered;

the adsorption structure 50 provides an air inlet 511, an air outlet 512, and at least one adsorption baffle 52 for directly contacting with the air flow to be filtered containing paint particles, wherein a non-horizontal flow passage is formed between the air inlet 511 and the air outlet 512, and the air flow flowing in from the air inlet 511 changes its flowing direction after meeting the adsorption baffle 52, and flows out from the air outlet 512.

And (3) second-stage filtration: providing a nozzle 41 and a vibrator 42 capable of spraying the powder;

in which a nozzle 41 sprays powder (especially lime powder, which will be described below by taking lime powder as an example) in a set direction toward an air flow to be filtered, the lime powder sprayed from the nozzle 41 settles by gravity on a receiving structure having a plurality of through holes 321, and the lime powder deposited on the receiving structure is discharged through the plurality of through holes 321 by the action of a vibrator 42.

And (3) filtering at the third stage: providing a filter 30 having a plurality of filter elements and periodically cleaning the surfaces of the filter elements;

wherein the paint particles contained in the air flow to be filtered are adsorbed and filtered by means of the filter element to obtain clean air and the clean air is discharged from the air outlet of the filter chamber 20.

Wherein, provide and sweep structure 60 and carry out regularly clearance to the filter core surface, sweep structure 60 and can form towards the surface of filter inner filter core and sweep the air current, this air current that sweeps cleans the lime powder deposit on filter inner filter core surface.

The following describes the implementation of the present invention in detail in connection with a preferred dry spray booth that can implement the method of the present invention for improving filtration performance of a dry spray booth:

as shown in fig. 2, the dry spray booth includes a spray booth 10 providing a spray painting work space, a filter chamber 20 providing a filtering work space, and a filter chamber 20 communicating with the spray booth 10, wherein a dry spray paint mist filtering system is provided in the filter chamber 20.

As shown by the arrow in fig. 2, part of the paint mist generated by the paint spraying chamber 10 during the painting operation, which does not fall onto the vehicle body, enters the lower chamber body 11 of the paint spraying chamber 10 under the effect of the compressed air in the paint spraying chamber 10, and because the side surface of the lower chamber body 11 is in a negative pressure state, that is, the air inlet 21 of the filter chamber 20 is in a negative pressure state, the paint mist and the air flow enter the filter chamber 20 along the air inlet 21 of the filter chamber 20 for filtering treatment.

The filtering chamber 20 is provided with a filtering system for filtering paint mist, the filtering system comprises a paint mist capturing unit, a spraying structure 40, an adsorption structure 50 and a purging structure 60, wherein the filter 30 in the paint mist capturing unit is a main place for fine filtering of air flow to be filtered containing paint particles by using a filter element, the spraying structure 40 is used for coarse filtering of the paint particles by spraying lime powder, the adsorption structure 50 is used for pre-filtering of large-particle paint mist in the air flow to be filtered by using a contact mode, and the purging structure 60 is used for anti-clogging treatment of the surface of the filter element of the filter 30.

As shown in fig. 2, a partition plate 31 and a lower plate 32 are provided at the windward port 21 of the paint mist trap unit, wherein the lower plate 32 provides a receiving space, and a gap is provided between the partition plate 31 and the lower plate 32 to form a space 30a through which the air flow to be filtered containing paint particles can pass.

The spraying structure 40 includes a powder nozzle 41, a vibrator 42, and a flow guiding plate 43, wherein the powder nozzle 41 is disposed in the space 30a, for example, fixed on the partition plate 31, for directionally spraying lime powder, the vibrator 42 is used for driving the lower plate 32 to vibrate, and the flow guiding plate 43 is used for receiving the lime powder.

The lower plate 32 is provided with a plurality of through holes 321, lime dust sprayed from the dust nozzle 41 falls on the lower plate 32, and under the vibration action of the vibrator 42, the lime dust falling on the lower plate 32 passes through the through holes 321 and falls down to the flow guide plate 43 to be collected.

The vibrator 42 of the present invention may be an electric vibrator or a pneumatic vibrator, wherein the vibration process of the vibrator 42 may be continuous or intermittent, and the vibration frequency of the vibrator 42 may be fixed or adjustable.

Wherein the filter 30 of the present invention is vertically disposed within the filtering chamber 20, for example, in the form of a clamp 33, for replacement and cleaning after a long period of use.

In the present invention, the lime powder sprayed from the powder nozzle 41 falls from above downward and forms a curtain through which a gas flow to be filtered containing paint particles flows in a horizontal direction toward the windward opening of the filter 30.

Specifically, the dust nozzle 41 is disposed at the lower side of the partition plate 31, and the dust nozzle 41 sprays the lime dust upward at an inclination angle R1 until the lime dust impinges on the lower side of the partition plate 31, wherein the lower side of the partition plate 31 may be further provided with a guide plate 311, and after the lime dust impinging on the lower side of the partition plate 31 is sufficiently dispersed, the lime dust falls freely downward under the guidance of the guide plate 311 to form the curtain so as to adsorb paint particles in the air flow to be filtered passing through the curtain.

Wherein the angle of inclination R1 is preferably 30-60, and the angle of inclination R1 is 45 as shown in FIG. 3.

Furthermore, the lower plate 32 of the present invention at least comprises a vertical plate 322 and a receiving plate 323, wherein the vertical plate 322 is vertically disposed in front of the powder nozzle 41 to block the sprayed lime powder, the receiving plate 323 is non-vertically disposed below the powder nozzle 41, and a plurality of through holes 321 are distributed on the receiving plate 323.

Specifically, the flow guide plate 43 is obliquely arranged below the receiving plate 323, and an included angle R2 between the receiving plate 323 and the flowing direction of the airflow to be filtered is provided, wherein the maximum included angle between the receiving plate 323 and the flowing direction of the airflow to be filtered is 45 °, an included angle R3 between the flow guide plate 43 and the flowing direction of the airflow to be filtered is provided, and R2 is not less than R3.

Fig. 3 shows a case where the angle R2 between the receiving plate 323 and the flow direction of the air flow to be filtered is 25 °, and a case where the angle R3 between the flow guide plate 43 and the flow direction of the air flow to be filtered is 50 °.

The filter 30 of the present invention further includes a mixing tank 34 and a grating 35, the lime powder collected on the flow guide plate 43 falls into the mixing tank 34 after passing through the grating 35, and the powder nozzle 41 is communicated with the mixing tank 34 through a connecting branch pipe to recycle the lime powder and reduce the use amount of the lime powder.

The adsorption structure 50 includes a box 51 and a plurality of adsorption baffles 52 disposed in the box 51, the box 51 has an air inlet 511 and an air outlet 512, under the blocking action of the adsorption baffles 52, a non-horizontal flow channel is formed between the air inlet 511 and the air outlet 512, and the air flow to be filtered flowing to the adsorption baffles 52 changes the flowing direction after encountering the adsorption baffles 52.

A preferred distribution mode of the plurality of adsorption baffles 52 is as shown in fig. 4, the plurality of adsorption baffles 52 are vertically disposed in the box body 51, two adjacent adsorption baffles 52 are an upper adsorption baffle 52a and a lower adsorption baffle 52b, respectively, wherein the box body 51 has an upper top plate 513 and a lower bottom plate 514, the upper end of the upper adsorption baffle 52a is disposed on the upper top plate 513, the lower end of the upper adsorption baffle 52a is suspended, the lower end of the lower adsorption baffle 52b is disposed on the upper bottom plate 514, the upper end of the lower adsorption baffle 52b is suspended, and a labyrinth flow passage is formed between the air inlet 511 and the air outlet 512 by the plurality of adsorption baffles 52.

The flow of gas within the tank 51 is shown by the arrows in fig. 4.

Specifically, in two adjacent adsorption baffles 52, the upper end of the lower adsorption baffle 52b is higher than the lower end of the upper adsorption baffle 52a, so that the airflow is in contact with the adsorption baffles 52 on the basis of ensuring the through-flow efficiency, and part of the paint mist is solidified and gathered on the surfaces of the adsorption baffles 52.

Tests prove that the air resistance of the adsorption structure 50 is small, the phenomenon of insufficient static pressure at the inlet of the circulating air fan is avoided, meanwhile, about 30% of paint mist can be captured by the adsorption structure 50, the paint mist amount entering the stone filter 30 is effectively reduced, and particularly when 2K varnish is adopted, the paint mist is easily solidified into paint skin paint when air meets, the effect of the adsorption structure 50 is more obvious.

In order to clean the adsorption baffle plate 52 conveniently, the adsorption baffle plate 52 and the flame-retardant film capable of being bonded are detachable, when the adsorption baffle plate needs to be cleaned, the flame-retardant film covered on the surface of the adsorption baffle plate is torn down and replaced after the adsorption baffle plate is detached, and the cleaning process is very convenient.

In other examples of the present invention, a plurality of directional holes 53 for the air flow to be filtered to pass through may be provided on the adsorption baffle 52, and the corresponding directional holes 53 on adjacent adsorption baffles 52 are distributed in a staggered manner, as shown in fig. 5, so as to achieve the effect of solidifying and gathering part of the paint mist on the surface of the adsorption baffle 52.

As shown in fig. 6, the blowing structure 60 includes a pulse air pipe 61 capable of generating air at a certain flow rate, and an air nozzle 62, the air nozzle 62 is located at an end of the pulse air pipe 61, the air nozzle 62 extends into a surface of a filter element in the filter 30 through an opening on a housing of the filter 30, referring to fig. 2, specifically, the air nozzle 62 is located right above the filter element in the filter 30, after the air nozzle 62 is opened, the filter element expands, lime powder and paint agglomerates on the surface of the filter element are shaken off, the shaken off lime powder and paint agglomerates fall on the grid 35, and the shaken off lime powder and paint agglomerates fall into the mixing tank 34 after passing through the grid 35, so that the lime powder can be recycled.

In addition, the invention can also provide a measuring device arranged at the air outlet of the adsorption structure 50, and the measuring device is used for detecting the airflow flow at the air outlet of the adsorption structure 50 so as to control the spraying speed of the powder nozzle 41 in a linkage manner and realize a more balanced adsorption effect.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the scope of the invention. It will be appreciated by those skilled in the art that variations may be made without departing from the scope of the invention, and equivalents may be resorted to without departing from the scope of the invention.

Claims

1. A method of improving the filtration performance of a dry spray booth for filtering paint particles produced by a spray booth in the dry spray booth, the method comprising:

a pressure difference between the painting booth (10) and the filtering chamber (20) forms a to-be-filtered air flow containing paint particles which directionally flows from the painting booth (10) to a windward opening (21) of the filtering chamber (20);

providing an adsorption structure (50) arranged in the flowing direction of the air flow to be filtered, and filtering paint particles contained in the air flow to be filtered in a first stage;

providing a nozzle (41) capable of spraying powder, wherein the nozzle (41) sprays the powder towards the airflow to be filtered in a set direction, and paint particles contained in the airflow to be filtered are filtered in a second stage;

wherein, the powder sprayed from the nozzle (41) is settled on a containing structure with a plurality of through holes (321) by gravity, a vibrator (42) which can drive the containing structure to vibrate is provided, and the powder accumulated on the containing structure is discharged through the through holes (321) under the action of the vibrator (42);

a filter (30) is provided for third stage isolated filtration of paint particles contained in the air stream to be filtered, to obtain clean air and to discharge the clean air from the air outlet of the filter chamber (20).

2. A method of improving filtration performance of a dry spray booth as claimed in claim 1, wherein a purge structure (60) is provided that extends into the surface of the filter insert in the filter (30), the purge structure (60) being configured to provide a purge flow of air against the surface of the filter insert in the filter (30), the purge flow cleaning dust deposits on the surface of the filter insert in the filter (30).

3. The method for improving the filtering performance of a dry paint spray booth according to claim 1, wherein the first stage of filtering is in the form of contact filtering, the adsorption structure (50) provides an inlet opening (511), an outlet opening (512), and at least one adsorption baffle (52) for direct contact with the air flow to be filtered containing paint particles, wherein a non-horizontal flow path is formed between the inlet opening (511) and the outlet opening (512), and the air flow flowing into the adsorption structure (50) from the inlet opening (511) changes its direction after encountering the adsorption baffle (52) and flows out from the outlet opening (512).

4. The method of improving filtration performance of a dry spray booth as claimed in claim 3, wherein a plurality of adsorption baffles (52) are provided, adjacent adsorption baffles (52) being staggered to form a wave-shaped labyrinth flow path between the adsorption baffles (52).

5. A method of improving the filtration performance of a dry spray booth as claimed in claim 3, wherein a plurality of adsorption baffles (52) are provided, each adsorption baffle (52) having a plurality of directional holes (53) for air flow therethrough, and wherein the directional holes (53) of adjacent adsorption baffles (52) are offset from each other.

6. A method of improving the filtration performance of a dry spray booth as claimed in claim 3, wherein a membrane is provided that is attachable to the adsorption barrier (52), the membrane is for adsorbing paint particles, and the membrane is detachable from the adsorption barrier (52).

7. A method of improving the filtering properties of a dry paint spray booth as claimed in claim 1, wherein the powder sprayed from the nozzle (41) falls from above downwards and forms a curtain through which the air flow to be filtered containing paint particles flows in a horizontal direction towards the windward side of the filter (30).

8. A method of improving the filtration performance of a dry spray booth as claimed in claim 7, wherein the nozzle (41) sprays the dust upwardly at an angle of inclination R1 until the dust impinges on a divider plate (31) for distributing the dust sufficiently that the fully distributed dust falls gravitationally to form a curtain of adsorbed paint particles.

9. The method of improving filtration performance of a dry spray booth of claim 1, wherein the containment structure provides:

an inclined receiving plate (323), the angle of inclination R2 between the receiving plate (323) and the direction of flow of the gas flow to be filtered being set to be less than 45 DEG, a plurality of through holes (321) being distributed on the receiving plate (323);

the inclined flow guide plate (43), the flow guide plate (43) is positioned below the containing plate (323), and the powder on the containing plate (323) passes through the through hole (321) and is collected under the flow guide of the flow guide plate (43);

wherein the inclination angle R2 between the receiving plate (323) and the flowing direction of the airflow to be filtered is set to be less than 45 degrees, the inclination angle between the flow guide plate (43) and the flowing direction of the airflow to be filtered is R3, and R3 is more than or equal to R2.

10. The method of improving filtration performance of a dry spray booth as claimed in claim 9, wherein a mixing chute (34), a grate (35) is provided, and the powder collected on the flow guide plate (43) falls into the mixing chute (34) after passing through the grate (35).