Scheme for Vacuum Cleaning System for Coal Dust Control in Belt Gallery

Fixed suction inlets and hoods shall be installed at key dust-generating points in the belt gallery (mainly at material drop points, transfer points, and under the return belt). Through the laid negative pressure pipeline network, the scattered coal dust is directly sucked into the pipeline by the negative pressure generated by the central high-power vacuum pump, transported to the dust collector for filtration and collection, and the purified air is discharged up to the standard.

Advantages of the Scheme:

Efficient dust removal: Capture dust directly from the source (scattering points), with efficiency much higher than traditional broom cleaning or water flushing. It can significantly reduce the dust concentration in the gallery (to below 10mg/m³).

Real-time operation: The system can be designed to operate in linkage with the belt conveyor, sucking dust in real time when the belt is running to avoid dust accumulation.

High degree of automation: Reduce or eliminate the need for manual cleaning, lowering labor intensity and safety risks (especially in high or narrow spaces).

Improved working environment: Greatly reduce secondary dust resuspension, protect workers' health, and comply with occupational health standards.

Reduced material loss: Collected coal dust can be recycled, reducing material loss.

Safety and Environmental Protection:

Eliminate potential dust explosion hazards (especially when the system design meets explosion-proof requirements).

Avoid water pollution (compared with water dust removal).

Meet emission standards and environmental protection requirements.

Easy Maintenance:

The system is centralized, with main maintenance points being dust cleaning of the dust collector and pipeline inspection.

System Composition and Key Design Elements:

Design and Layout of Dust Suction Points (Most Critical)

Location: Focus on covering all areas below material drop points and transfer points, the tail escape area of the guide chute, under the return belt (especially near the head pulley, where dust is easy to accumulate), and under the belt cleaner. Consider the scattering area possibly caused by belt misalignment.

Design of Suction Hoods/Inlets:

Type: Select appropriate suction hoods according to scattering characteristics, such as slotted suction inlets (suitable for along the belt), umbrella-shaped/receiving hoods (suitable for material drop points), and enclosed chambers (suitable for severe escape points).

Sealing: Improve the sealing between the suction hood and the dust source as much as possible (e.g., using soft curtains, rubber skirts) to reduce invalid air intake and improve capture efficiency.

Air velocity and volume: Sufficient control air velocity (usually ≥0.5-1.0 m/s for coal dust) shall be maintained at the opening of the suction inlet/hood to ensure effective dust suction. The required air volume for each suction point shall be calculated.

Wear resistance: Suction hoods, inlets, and nearby pipelines shall consider coal dust scouring and use wear-resistant materials (e.g., wear-resistant steel plates, ceramic liners, wear-resistant elbows).

Negative Pressure Pipeline Network:

Material: Preferred wear-resistant carbon steel pipes (with inner wall wear-resistant treatment such as ceramic tiles, wear-resistant coatings) or ultra-high molecular weight polyethylene pipes. Avoid ordinary PVC (easy to wear and accumulate static electricity).

Pipe diameter: Determined according to the total air volume of the system, air volume balance of each branch, and economic flow velocity (usually 15-25 m/s). Main pipelines are usually larger (DN200-DN400 or larger), and branch pipes are gradually reduced.

Layout:

Tree-like structure: Most common, with main pipes laid along the belt gallery and branch pipes connected to each suction point.

Loop structure: Suitable for particularly long galleries, helping to balance system pressure loss.

Slope: Horizontal pipelines shall be sloped (≥1%), and ash cleaning ports/discharge valves shall be set at low points to prevent dust deposition and blockage.

Elbows and reducers: Use elbows with large curvature radius (R/D ≥ 1.5) to reduce resistance and wear. Reducers adopt tapered/reducing pipes.

Valves: Install manual or pneumatic control valves on each branch for air volume balance during system commissioning. Isolation valves may be required for main pipelines.

Central Vacuum Power Unit:

vacuum cleaning system pump:

Type:

Roots blower: Most commonly used, providing high negative pressure and constant flow characteristics, suitable for long-distance, multiple suction points, and high negative pressure requirements. Preferred.

Centrifugal fan: Suitable for systems with large air volume, relatively low negative pressure requirements, and short pipelines. It may have higher efficiency, but its characteristic curve is easily affected by changes in system resistance.

Air volume and negative pressure: Selected according to the total air volume requirement of the system (sum of air volumes of all suction points + air leakage coefficient) and total system resistance (pipeline resistance + suction hood resistance + dust collector resistance + safety margin). Coal dust systems usually require high negative pressure (-15 kPa to -50 kPa or higher, depending on system scale and complexity).

Explosion-proof: Must use explosion-proof motors and fans that meet the requirements of explosion-proof areas (Ex d IIB T4 or higher, depending on coal dust characteristics).

Silencer: Installed at the inlet/outlet of the fan to reduce operating noise.

Control system: Integrate start-stop, pressure monitoring, fault alarm, interlock control with the belt conveyor, etc.

Dust Collection System:

Type selection:

High-efficiency pulse-jet bag filter: Most commonly used and recommended. High filtration efficiency (>99.9%), large air handling capacity, suitable for fine dust. Filter materials must be anti-static and flame-retardant (e.g., anti-static polyester film-coated, P84, etc.).

Cartridge dust collector: Compact structure, large filtration area, relatively easy maintenance. Anti-static and flame-retardant filter materials are also required.

Cyclone separator: Usually used only as a pre-separator, connected in series with bag/cartridge filters to reduce the load on the main filter.

Key design:

Filtration area: Calculated according to the handling air volume and filtration air velocity (0.8-1.2 m/min is recommended for coal dust). With margin reserved.

Dust cleaning method: Pulse jet cleaning is most commonly used, ensuring thorough and reliable cleaning.

Hopper and ash discharge: Hopper design shall ensure smooth ash discharge and avoid dust accumulation. Equipped with rotary discharge valves or double-layer flap valves for continuous/intermittent ash discharge. Hoppers shall be equipped with level gauges and vibrators (if necessary).

Explosion-proof Safety:

Explosion venting panels: Installed on the dust collector body and hopper, facing safe areas.

Flame arrester valves: Installed on the inlet pipeline of the dust collector to prevent explosion propagation back to the pipeline.

Fire extinguishing system: CO2 or inert gas fire extinguishing devices may be considered for high-risk areas.

Static electricity discharge: All components are reliably grounded, and filter materials are anti-static.

Temperature/CO monitoring: Optional monitoring of internal temperature or CO concentration to warn of smoldering.

Emission: Purified air is discharged up to the standard through the exhaust stack (meeting ≤10mg/m³ or local standards). The height of the exhaust stack meets requirements.

Control System:

Core functions:

Start-stop control of the vacuum pump.

Interlock with the belt conveyor: When the belt starts, the vacuum cleaning system starts automatically (can stop with delay); when the belt stops, the cleaning system stops after running for a period of time (to suck residual dust).

Monitoring and display of system operating parameters (vacuum degree, fan current, filter differential pressure).

Fault alarm (excessive differential pressure, fan overload, high material level, etc.).

Automatic control of the dust collector cleaning program.

Optional: Remote monitoring (SCADA), zoned control (for ultra-long galleries).

Implementation Steps:

Detailed investigation: Measure the length, height, and layout of the belt gallery; identify all dust sources (number, location, drop height, material flow rate, belt width/speed of material drop points); evaluate existing dust conditions (concentration, accumulation); understand on-site power supply and space constraints.

The vacuum cleaningSystem design:

Determine the location, quantity, and required air volume of each suction point.

Design pipeline layout drawings, calculate pipe diameter, total system air volume, and total resistance.

Select vacuum pump (air volume, negative pressure, explosion-proof grade).

Select dust collector (type, filtration area, explosion-proof measures).

Design control system scheme.

Conduct explosion risk assessment (ATEX/DSEAR, etc.) and ensure all designs comply with relevant safety specifications.

Equipment procurement and manufacturing: Procure explosion-proof fans, anti-static dust collectors, wear-resistant pipeline valves, etc., that meet specifications.

Installation and construction:

Construct strictly according to design drawings, paying attention to pipeline slope, support, and sealing.

Ensure explosion-proof installation of all electrical equipment.

Reliable grounding.

Commissioning and acceptance:

Inspect pipeline air tightness.

Conduct individual fan test run.

Operate the system under no-load, adjust valves of each branch to balance air volume.

Operate under load, test the capture effect of each suction point.

Measure dust concentration in the gallery and at the emission outlet to ensure compliance.

Train operators and maintenance personnel.

Operation and Maintenance:

Regularly inspect pipeline wear and leakage.

Regularly clean hoppers and replace filter bags/cartridges as planned.

Inspect the operation of fans and valves.

Record operating parameters and maintenance logs.

Special Notes:

Explosion protection is a top priority: Coal dust is explosive. The entire system (fans, motors, dust collectors, pipelines, valves, electrical instruments, control systems) must be designed and selected strictly in accordance with dust explosion hazard zoning and relevant standards (e.g., ATEX, IECEx, NFPA 654, GB 15577). Attach importance to explosion venting, flame arrester, explosion suppression measures, and static electricity control.

Wear resistance: Coal dust is abrasive; wear-resistant measures must be adopted for pipelines, suction inlets, and easily worn parts inside the dust collector.

Moisture proofing and anti-caking: If the humidity of coal dust may change, measures to prevent dust from absorbing moisture and caking in pipelines or hoppers shall be considered (e.g., heat preservation, heat tracing).

System balance: Accurate calculation and commissioning to ensure reasonable air volume distribution at each suction point, avoiding insufficient suction at some points and waste of air volume at others.

The vacuum cleaning system is an efficient, advanced, and sustainable solution for controlling coal dust scattering in belt galleries. Its core lies in source capture, closed conveying, and centralized filtration. The key to successful implementation is accurate design of suction points, reasonable pipeline calculation and layout, selection of reliable explosion-proof vacuum power and dust collection units, and strict explosion-proof safety measures. Although the initial investment is relatively high, its long-term benefits in improving the environment, ensuring safety, reducing operating costs (labor, material recycling, reducing equipment wear), and improving production efficiency are significant. It is essential to entrust professional companies with rich experience in dust control and explosion protection for design and implementation.