A, the principle of spraying recovery device
Electrostatic powder spraying recovery device from the environmental protection equipment in the dust removal device, its basic function is to achieve the two-phase separation of gas and solid mixed fluid, the difference is that the solid phase of the dust removal for waste, while the recovery of the solid phase is the use of materials, with a variety of structures of filter bags, cartridge separator as the main filtering equipment, the principle of its work is through the role of the screen filter media to intercept the powder.
Second, the classification of the recycling device
The coating industry from the perspective of the combination of equipment configuration of the recycling device, it will be divided into a recycling, two recycling, and even three recycling.
1. The first level of recovery only uses the filter separator to complete the recovery of powder, usually designed with a single integrated powder spraying room.
2. The second recycling refers to the recycling system formed by cyclone separator and filter separator in series, which is most common in the existing electrostatic powder coating production line.
3. Three levels of recovery is based on the second level of recovery, and then connected in series with a filter separator, only for special environmental requirements of the occasion.
1.1 One-stage recycling device of integrated powder spraying room cartridge
A number of cartridges are set directly in the powder spraying chamber operating port, opposite the composition of the integrated powder spraying chamber cartridge primary recovery device is a more common configuration.
When powder spraying operation, the floating powder not adsorbed on the workpiece to be painted is pumped with the indoor air by the exhaust fan and flows to the cartridge opposite to the operation port, after filtering by the cartridge made of parchment and other filter media, the powder is retained in the room, while the air is discharged to the outdoors through the filter core. In this way, when the compressed air is used regularly to blow back the cartridge, the powder on the surface of the cartridge falls into the collection box at the bottom of the chamber, and can be recycled. Continuous exhaust air not only maintains the negative pressure in the room, the powder can not spill, but also to ensure that the concentration of dust in the room does not exceed the explosive boundary.
The advantages of this recycling configuration is compact, small footprint, because no connected pipeline, so maintenance, cleaning are very convenient, and relatively small investment in equipment. The disadvantage is that the recovery burden of the cartridge is heavy, easy to clog, damage, in addition to the installation of the cartridge side can not set the operating port, so it is appropriate to be used for the powder spraying volume is not large, the recovery burden of light occasions.
2.1 Single-tube cyclone plus bag filtration composition of the secondary recovery device
Single-tube cyclone separator is commonly known as “big cyclone”. When the air inlet with a pipeline and the extraction port of the powder room (standing at the bottom of the powder room) connected, and the air outlet with the bag filter separator air inlet connected, it constitutes a single-tube cyclone plus the bag filter secondary recovery device.
This secondary recovery device work, the air and powder mixture from the powder room into the single-tube cyclone separator first. In the high-speed cyclone centrifugal action, more than 80% of the larger particle size of the powder are along the cyclone wall into the bottom of the tube, containing a small amount of fine powder air into the bag filter separator for filtration and separation. Because of the role of the two-stage device, so it can withstand the larger recovery load, the recovery rate of more than 95%.
This two-stage recovery configuration in the design of the structure of the powder spraying room can be achieved without occupying the operating position on both sides, so it is conducive to the spraying operation of larger workpieces.
The disadvantage is that it covers a large area, especially the large cyclone internal and recovery pipeline cleaning inconvenience, so it is not suitable for frequent color change of electrostatic powder coating.
2.2 Multi-tube cyclone plus cartridge filtration constitutes the secondary recovery device
This recovery configuration of the connection relationship and the effect of the large cyclone plus bag recovery configuration is similar. The difference is: multi-tube cyclone (also known as small cyclone) using a multi-tube structure to replace the single tube of the cyclone, so it is shorter, relatively easy to clean up.
In addition, the cleanup or replacement of the filter element is also easier than the bag. Suitable for powder spraying workload and have a color change requirements of the occasion. The disadvantage is that the investment cost of equipment is higher, the specifications can be selected less.
When the use of secondary recovery, usually cyclone separator separated from the large particle size powder can be directly reused. There are two methods of recovery: one is to manually time the cyclone at the bottom of the collection of powder barrel removed, the recovery of powder after sieving back to the powder supply device; the second is with the so-called closed-circuit recovery system automatically back to use, that is, through the installation of the collection of powder barrel on the venturi powder pump, under the action of compressed air, slowly the recovery of powder back to the powder supply device. Obviously, the powder spraying workload is larger, especially the continuous production of electrostatic powder coating line, the second recovery method should be used.