Low-pressure long bag pulse bag dust collector
I. Overview
The Low-Pressure Long Bag Pulse Bag Dust Collector is a mainstream and efficient dust removal equipment in the field of modern industrial flue gas purification. It integrates two core technologies: "Long Filter Bags" (usually over 6 meters in length, up to 8-10 meters), and "Low-Pressure Pulse Jet Cleaning." It features high air volume handling capacity, high dust removal efficiency, small land occupation, and stable and reliable operation, widely used in various large-scale industrial dust control scenarios.
II. Working Principle
The process can be summarized into two main stages: "filtration" and "dust removal."
1. Filtration process
Dust-laden gas enters the dust collector through the inlet, after passing through the air distribution plate, large particles of dust fall directly into the ash hopper due to gravity, providing a preliminary dust removal effect. The gas then uniformly passes through the filter bags, with dust being trapped on the outer surface (outer filtration) or inner surface (inner filtration, such equipment is mostly of outer filtration type). The purified clean gas enters the interior of the filter bags, collects upwards to the clean gas chamber in the upper housing, and is finally discharged through the outlet.
2. Dust removal process
As the dust layer on the outer surface of the filter bag thickens, the operation resistance (pressure difference) of the dust collector will gradually increase. When the resistance reaches the preset value (or the dust removal time interval expires), the PLC control system will automatically initiate the dust removal program.
Low-pressure pulse jetting: The electromagnetic pulse valve opens instantaneously (approximately 0.1-0.2 seconds), expelling compressed air stored in the jet pipe (typically at a pressure of 0.2-0.4 MPa, lower than the traditional pulse's 0.5-0.7 MPa, hence the term "low-pressure") at a high velocity through the venturi tube of the jet opening (now often omitted in many designs). This high-speed airflow induces several times its own volume of air, creating a strong reverse airflow that enters the filter bag, causing it to急剧 inflate and vibrate, thereby dislodging the dust layer adhering to the outer surface of the filter bag into the ash hopper. Cleaning is done in separate batches, with only one or a group of filter bags being cleaned at a time, ensuring the dust collector operates continuously without interruption.
III. Core Features and Advantages
"Long Bag" technology
Compact land area requirement: By using longer filter bags under the same filtering area, the footprint of the dust collector can be significantly reduced, saving on land and steel costs.
High air volume handling: A single unit can easily achieve air volume handling capacities of up to several hundred thousand cubic meters per hour.
2. "Low-Pressure Pulsing" technology
Low energy consumption: Lower injection pressure requirements reduce the consumption of compressed air and lower operating energy consumption.
Minimal damage to filter bags: Lower pressure indicates a gentler cleaning force, effectively extending the lifespan of the filter bags.
Excellent dust removal effect: Optimized blast pipe and nozzle design, combined with the concept of low pressure and high flow, achieves effective and uniform dust removal, ensuring the equipment operates stably at low resistance for extended periods.
3. High dust removal efficiency
For particulate matter at sub-micron levels (<1μm), dust removal efficiency can effortlessly reach over 99.9%, with emissions concentrations consistently below 10 mg/m³, and even dipping below 5 mg/m³, meeting the world's most stringent environmental emission standards.
4. Intelligent Control
The automatic control system utilizes PLC and a touch screen to achieve various cleaning modes, including differential pressure cleaning, timed cleaning, and manual cleaning. It boasts a high level of automation and is easy to operate and maintain.
IV. Main Structure Composition
1. Structural Frame: The main supporting structure of the equipment.
2. Case: Includes the middle case (filter chamber) and the upper case (clean air chamber). Typically features a modular design for easy transportation and installation.
3. Dust Pan: Used for collecting the dust that falls during cleaning, equipped with a discharging device at the bottom (such as a star discharge valve or a silo pump).
4. Filter Bags and Skeletons (Cage)
Filter Bags: The core of dust collectors, materials are selected based on the characteristics of flue gas (temperature, acidity/alkalinity, humidity, etc.), such as PPS, P84, PTFE-coated, glass fiber, etc.
Frame (Cage): Supports the filter bag to prevent it from being collapsed. For long bags, the frame needs to have sufficient strength and verticality, usually adopting a multi-section structure.
5. Blowing System
Gas Storage Tank: Supplies a stable gas source.
Pulse valve: A critical actuating component for the dust removal action, requiring fast response and long service life.
Blow-off tube: Directs compressed air evenly to each filter bag.
6. Intake and exhaust air openings: Rational air flow organization design.
7. Airflow Distribution Device: Ensures that dusty gases are evenly distributed into each filter chamber, preventing localized flushing of the filter bags.
8. Ladder guardrails and inspection doors: Used for routine inspections and maintenance.
9. Control System: PLC electric control cabinet for automated operation.
Factory Production
V. Main Application Fields
This dust collector is almost suitable for all industrial sectors that generate large amounts of dust.
Cement industry: crushing, grinding, drying, packaging, kiln head and tail, and the entire process.
Iron and steel metallurgy industry: Sintering, ironmaking, steelmaking, coking, iron alloys, etc.
Power Industry: Fly ash collection for power plant boilers, coal-fired boilers, and biomass boilers.
Non-ferrous metal smelting: copper, aluminum, lead, zinc smelting flue gas treatment.
Waste Incineration: Dust purification of flue gases.
VI. Advantages Analysis
High Efficiency, Low Consumption: Extremely high dust removal efficiency with low operating energy consumption (especially low gas consumption).
Compact footprint: The long bag design offers distinct advantages in large-scale projects.
High Reliability: Mature technology, reasonable structure, low failure rate.
Ease of Maintenance: Filter bag replacement can be done in the clean air chamber, and the modular design allows for online maintenance.
Section 7: Selection and Design Considerations
1. Filter Air Velocity: A core parameter. It needs to be determined based on dust characteristics, concentration, temperature, etc. For long-pulse dust collectors, the filter air velocity is generally lower, usually between 0.6-1.2 m/min.
2. Filter Material Selection: Choose the most suitable filter material and post-treatment process based on the temperature, chemical composition, humidity, and other conditions of the flue gas.
3. Blowing System Design: The size, quantity, and distance of the blowing tube holes from the perforated plate require precise calculations and experimental verification to ensure uniform dust cleaning force for each filter bag.
4. Airflow Distribution: Large dust collectors require the installation of airflow distribution plates or guide plates to prevent airflow short-circuiting and filter bag wear.
5. Insulation and Corrosion Resistance: For handling high-temperature, high-humidity, or corrosive flue gases, the cabinet must be insulated and corrosion-resistant treated.