Context

An engineering and consulting company contacted ISERCO for the supply of a big bag filling project with pneumatic transport of wood fines. This installation is intended for a client of the public heat distribution service.

This Big Bag project, awarded to ISERCO, is necessary to recycle wood dust from the unclogging of 2 bag filters located in the boiler plant’s fuel storage area.

The customer wants to recycle these fines because, despite the containment systems installed, they cause significant contamination of the equipment.

The customer’s requirement was therefore to find a solution that would not reintroduce the fines into the conveying circuit in order to reduce the amount of dust transported. Recycling must take place outside the handling process.

The site is located on a railway site.

Project constraints

There are a number of requirements for this project.

The first constraint is the potentially flammable nature of the product to be packed into big bags. The various falls during the handling process generate clouds of potentially ATEX-risk dust collected by several bag filters.

This dust-related constraint requires appropriate measures to offset the risk of ignition or explosion. For this reason, the installation must comply with a number of rules.

In particular, all equipment must:

  • Be equipped with integral dust protection and protection against water jets for various electronic or electrical equipment.
  • Be compliance with several directives (conformity of machinery, electrical installations in potentially explosive atmospheres other than mines, pressure equipment directive, ATEX directive, etc.).
  • Use big bags with anti-static properties.

Another constraint imposed on this project relates to the noise measurement campaign, the aim of which is to limit daytime and night-time noise pollution. The installation must be limited to a noise level of 76 dB in order to comply with the Prefectoral Decree. For this purpose, performance tests are planned. This part will be subcontracted to a specialised and certified office to measure the noise levels and emissions of the installations in operation.

The proposed solution

The solution chosen for recycling the fines was to install a big bag system to reduce the quantity of dust transported. This installation is located close to the 2 bag filters from which the fines are extracted.

All the equipment consists of:

  • A steel big bag filling station with :
    • A steel structure.
    • A weighing sleeve.
    • A corrugated sheath and a process connection.
    • An extension table with ATEX 22 pneumatic cylinder.
    • 2 round steel forks.
    • A dual stream spout filling head with inflatable seal. It also has an ATEX 21 electro-pneumatic internal shut-off valve and 2 taps with an ATEX 21 electro-pneumatic internal shut-off valve.
    • ATEX 21 preforming fan.
    • A weighing system with 4 load cells and weighing indicator.
    • A pneumatic control board controls the entire station, with connections between the cabinet and the ATEX 22 equipment.
  • A frame with a steel buffer hopper consisting of:
    • A tubular steel frame.
    • A 1m3 capacity buffer hopper with a vibrating motor, 4 silentblocks, a high-level probe, a filter bag and an explosion vent.
    • An ATEX 20 internal and ATEX 22 external electro-pneumatic butterfly valve.
    • A maintenance access bridge.
    • A crinoline ladder.
  • A flame trap on the vent.
  • Cladding for the structure.
  • F5 filter door and cladding.
  • ATEX 21 pneumatic transport system with :
    • An injection pump.
    • A pneumatic steel transport injection hopper with 2 vibrating fork level probes, an injector and a 2-way distributor.
    • A pneumatic steering system.
  • Another ATEX 21 pneumatic conveying system with double suction pump with:
    • A double injection pump.
    • A pneumatic transport injection hopper equipped with 2 vibrating fork level probes, an injector and a 2-way distributor.
    • A pneutimer.
    • One purge valve.
    • 50 m of earthed rigid pipework.
    • 2 m of flexible piping.
  • 10 m of compressed air piping for connection between the customer’s network and the ISERCO pneumatic cabinet.

The steel finish of the filling station, frame and buffer hopper is a lacquered galvanised finish.

In addition to supplying the above elements, ISERCO was responsible for:

  • Study and functional analysis of the project.
  • Mechanical assembly of the equipment.
  • Production tests.
  • Commissioning and operator training.

Bulk information

  • Industry: Heating Company
  • Product type: Wood dust (biomass fuel)
  • Density: 0.42
  • Particle size: Fine particles from pellets
  • Installation zone: ATEX – Fire – Explosion
  • Big bag size: 1m3