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The flat bag cage is a dust removal frame specially designed to cooperate with envelope-type filter bags (also known as flat bags or flat plate filter bags). It is in the shape of a flat rectangle or envelope and is made by spot welding or ring welding high-strength steel wire (usually low-carbon steel wire, stainless steel wire or galvanized steel wire) with professional welding equipment. | |||||||||
Alternative names
Envelope bag cage
Flat bag frame
Flat bag cage
Envelope-style skeleton
Flat frame
(Sometimes it is also called a rectangular bag cage according to its specific shape.
Product Introduction
The flat bag cage is a dust removal frame specially designed to cooperate with envelope-type filter bags (also known as flat bags or flat plate filter bags). It is in the shape of a flat rectangle or envelope and is made by spot welding or ring welding high-strength steel wire (usually low-carbon steel wire, stainless steel wire or galvanized steel wire) with professional welding equipment.
Its main function is to support the filter bags, prevent them from being sucked in or overly deformed during the filtration and cleaning processes, ensure the smoothness of the filtration air flow channel, improve the cleaning effect, and extend the service life of the filter bags. It is a key internal component in bag filters, especially pulse-jet filters.
Product Features
Flat structure: The core feature is that the cross-section is rectangular or envelope-shaped, significantly saving the internal space of the dust collector.
High space utilization: Within the same volume of the dust collector box, a larger filtration area can be arranged than that of circular filter bags/bag cages (usually increasing by 30%-50% or even more), which greatly improves the dust removal efficiency or reduces the equipment volume.
Lightweight design: Compared with the circular bag cage system required to handle the same air volume, the overall weight is usually lighter.
High rigidity and stability: The design features sufficient longitudinal ribs and support rings (or special grid structures) to ensure shape stability under negative pressure or ash cleaning spray pressure, preventing filter bag collapse.
Smooth surface treatment: The surface undergoes smooth treatment (such as galvanization, powder coating, silicone spraying, etc.) to reduce friction damage to the filter bags, facilitate dust shedding (good dust cleaning effect), and enhance corrosion resistance.
Easy to install and replace: The structural design usually takes into account installation convenience (such as the top Venturi tube or chuck design), facilitating the insertion and fixation of filter bags.
Strong adaptability: Customized for envelope-type filter bags of various specifications and sizes.
Application scenarios
Flat bag cages are widely used in pulse-jet bag dust collectors that require high filtration efficiency, compact space design or large air volume handling. They are commonly found in:
Cement industry: Dust collection in high-temperature and high-dust sections such as kiln head, kiln tail, coal mill, and cement mill.
Steel and metallurgy: head and tail of sintering machines, purification of blast furnace gas, secondary flue gas from converters, flue gas from electric furnaces, ferroalloy smelting, etc.
Power industry: Flue gas dust removal for coal-fired boilers (especially in renovation projects with limited space).
Chemical industry: Dust recovery and flue gas purification in various technological processes.
Waste incineration power generation: Purification of flue gas from incinerators.
Aluminum industry: Purification of electrolytic aluminum flue gas.
Food, medicine, woodworking: Dust collection and air purification.
In any dust removal situation where space is limited or a higher filtration efficiency per unit volume is pursued.
Product Advantages
Significantly save equipment investment and space: The high filtration area/volume ratio makes the dust collector design more compact, reducing civil construction and equipment costs.
Enhance processing capacity: Handle a larger air volume within a dust collector of the same size.
Reduce operating resistance: A reasonable structural design and good ash cleaning effect help maintain a lower system resistance.
Extend the service life of filter bags: Good support and smooth surface reduce mechanical wear and stress concentration of filter bags.
More thorough ash cleaning: The flat structure enables the pulse airflow to act more evenly and effectively on the entire surface of the filter bag.
Low maintenance cost: The filter bags are relatively easy to replace and have a long service life.
High reliability: The robust structural design ensures long-term stable operation.
Customized process
Due to the different models of dust collectors and the various sizes of filter bags, flat bag cages usually need to be customized.
Demand communication: The customer provides the model of the dust collector, drawings, or clearly states the required filter bag dimensions (length, width/circumference, installation method, etc.), working conditions (temperature, humidity, corrosiveness, dust characteristics, etc.), material requirements, and surface treatment requirements.
Design Confirmation: The supplier conducts the design based on the customer's requirements (including structural form, number and spacing of longitudinal ribs/support rings, top connection method, bottom structure, etc.), and provides drawings or solutions for the customer's confirmation.
Sample confirmation (optional but recommended): For important projects or new specifications, samples can be made first for trial installation to verify their compatibility with filter bags and dust collector flower plates.
Signing the contract: Sign the contract after confirming the details such as design, price, and delivery date.
Raw material procurement: Purchase steel wire that meets the requirements (material, diameter).
Production and Manufacturing
Straighten and cut the steel wire.
Welding: Use a dedicated welding machine (mostly multi-head automatic welding machines) to precisely weld the longitudinal ribs to the support rings/transverse ribs to form a frame structure. Strictly control the quality and spacing of solder joints.
Shaping: Ensure that the frame is straight and free from distortion and deformation.
Surface treatment: Galvanization, high-temperature silicone spraying, powder coating or other anti-corrosion treatments are carried out as required. Strictly control the thickness and uniformity of the coating.
Inspection and packaging: After passing strict quality inspection, it is properly packaged (usually individually sealed with plastic or wrapped in anti-rust paper, neatly stacked in wooden or iron boxes) to prevent deformation and rusting during transportation.
Delivery and Shipment: Deliver the goods as required by the contract.
Quality Inspection process
Strict quality control is the key to ensuring the performance and lifespan of bag cages
Raw material inspection: Check the steel wire material certificate (quality guarantee certificate), diameter, and surface quality (no rust, oil stains, cracks, etc.).
Dimensional accuracy inspection
Total length, width (or perimeter), diagonal length.
Longitudinal bar spacing, support ring (transverse bar) spacing.
Perpendicularity/straightness: Ensure that the frame is free from bending and distortion.
The size of the top flange (chuck), the matching of the hole position and the flower plate.
Bottom structure dimensions.
(Measure using calipers, tape measures, Angle gauges, special inspection tools, etc.)
Welding quality inspection
Solder joint strength: Conduct tensile tests (spot checks or destructive tests) to ensure that the solder joints can withstand the specified tensile force without delamination.
Appearance of solder joints: The solder joints are uniform and full, without false soldering, missed soldering, overburning, burrs or welding slag. Burrs must be ground smooth.
Welding firmness: Manually check for any loose weld points.
Structural stability inspection: Manually apply force to check the overall rigidity and anti-deformation capacity.
Surface treatment quality inspection:
Coating appearance: Uniform, smooth, free of sagging, missed spraying, bubbles and impurities. The color meets the requirements.
Coating thickness: Use a coating thickness gauge for detection to ensure it meets the standards (for example, for silicone spraying, it is usually required to be >80μm).
Adhesion test (random inspection) : such as cross-sectional test, to test the bonding strength between the coating and the substrate.
Corrosion resistance test (random inspection or batch test) : such as salt spray test (in accordance with standards like GB/T 10125), to evaluate the anti-corrosion performance.
Cleanliness inspection: There should be no oil stains, dust, welding slag or other foreign substances inside or outside the product.
Packaging inspection: The packaging should be firm, with clear labels (specifications, quantities, production dates, batch numbers, etc.), and be capable of effectively preventing moisture and impact.