Wood chips in the Energy Industry

AIR TECHNIC designs and supplies technological equipment for biomass (wood chips) drying in power engineering. The robust construction of the dryers allows drying of brown forest wood chips (chips with mineral additives) up to a particle size of P100.The purpose of the technological equipment is to dry the biomass, respectively reduction of water content in biomass due to an increase in energy value (calorific value).

• The moisture content in wood chips at the inlet to the dryer up to 60%

• The moisture content in wood chips at the outlet dryer can be reduced to below 5%.

Technological equipment for drying wood chips consists of a separate wood chips dryer and AHU for supplying drying air to the dryer and natural or forced extracting of saturated air from the dryer.

The continuous conveyor dryer uses low-grade waste heat and drying air at temperatures of 80–95°C to reduce the moisture content of wood chips.

For heating of the drying air can be used various heat sources:

• warm water, hot water, steam

• natural gas, LPG

• flue gas

Biomass dryers capacity depends on the volume of evaporated water given by the inlet and outlet moisture content of wood chips and the drying air temperature, respectively heat source power:

• Dryer S2 (up to 4 t/h)

• Dryer S4 (up to 12 t/h)

• Drying of larger volumes of wood chips is achieved by the parallel arrangement of dryers.

Fig. Wood chips dryers S4 (2 pcs), incl. cover and ventilation system for exhausting most air (C-energy s.r.o., Planá nad Lužnicí)

Fig. Wood chips dryer S2, without cover and ventilation system

AIR TECHNIC s.r.o. designs and supplies systems for receiving, conveying, screening, shredding, crushing and storing wood chips in the energy industry.

For the receiving and entry of the transported material into the machine transport system, we use:

• Hydraulic sliding floors

• Screw fields

To ensure the protection and availability of downstream technology, the transported material is sorted and processing:

• A magnetic separator with automatic cleaning is used to separate ferromagnetic particles

• For screening oversized material, we use robust disc screens of our own design

• For shredding and crushing the sorted oversized material, crushers with elements made of wear-resistant steel (Hardox) are used

For wood chips conveying we use:

• chain conveyors

• belt conveyors

• screw conveyors

• vibrating conveyors

For pressure separation of the fuel and boiler transport routes, we use heavy duty rotary feeders with temperature resistance up to 850°C.

An essential part of material transport are chutes and transport chutes made of abrasion-resistant materials (Hardox, plastic) with the possibility of monitoring overcrowding (collapse) and vaulting.

For storing of the transported material in energy industry are used Steel or Concrete silos with an automatic discharge systems and Chain conveyors with an open bottom.

Fig. Two independent transport and processing lines - with sliding floors, Fe material separation, disc screening, crushing, conveyors and a common silo (Teplárna Strakonice a.s.-K1K2)

AIR TECHNIC s.r.o. designs and supplies wood chips storage silos and bunkers in energy industry.

To ensure high reliability of fuel handling systems in energy industry (supplying the boiler with fuel), wood chips storage silos with an active flat bottom are used.

Elimination of wood chips vaulting (bridging) in storage silos and uniform distribution of fuel to subsequent transport routes is ensured by correct storage silo design, sliding floors or a rotary crusher at the bottom of the storage silos.

The design of storage silos allows for the simultaneous filling of up to four subsequent screw conveyors.

Ventilation of the storage silo and elimination of dust spread from the storage silo can be solved by installing a filter ventilation device with dust extraction directly into the storage silos.
The storage silos can be equipped with a system for eliminating and suppressing explosions in the initial phase.

For storing larger volumes of wood chips, circular concrete silos with a rotary screw conveyor for automatic discharge are used.

Fig. Wood chips silo with sliding floors (Plzeňská teplárenská a.s. - K7)