Waste recycling

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Currently, the issue of energy conservation and, therefore, waste regaining is acute for the whole world. In light of continuously growing prices of energy products, there is growing interest in alternative biologically clean energy sources.

Wood processing industry leaves a large amount of waste in the form of sawdust, shavings, wood chips, etc. Wood-processing enterprises accumulate a huge amount of waste, which raises the question of its utilization and, therefore, leads to additional costs. However, there are more sustainable ways

of using it.

This article deals with recycling of wood waste. It considers briquetting technology, as well as equipment for production of fuel briquettes.

Since 2007 our company has been engaged in production of equipment for briquetting of wood and agricultural waste. Today we occupy a leading position in Ukraine in producing briquetting equipment.

Let us consider wood waste briquetting line based on our equipment. A briquetting process consists of several stages:

– Stage 1: Wood shredding by a shredding complex.

– Stage 2: Aerodynamic drying of sawdust.

– Stage 3: Briquetting by hit-mechanic press.

As an example, let’s take large wood waste with natural humidity. In this example, briquetting process is composed of the above listed stages.

The first stage of briquetting process: Shredding.

Shredding equipment consists of a disc crusher or a shredder (primary crushing), a chip metering hopper and a hammer crusher. In this example, we will consider a disk crusher. Let’s get started.

Large wood waste is delivered to the shredder RM 800.4. It is a stationary disk shredder designed for shredding wood waste: laths, slabs, etc. Shredder knives crush wood waste into chips ranging from 8 to 20 mm. From RM 800.4 chips fall into chip collection bin. Bin is designed for uniform feed of wood chips to the shredder RM 800.7. From collection bin wood chips get through a screw conveyor feed into the shredder RM 800.7, where chips are crushed by hammers into fraction of 1 to 10 mm.

The second stage of briquetting process: Aerodynamic drying of sawdust.

Chopped raw material gets from shredder RM 800.7 into a metering hopper of aerodynamic dryer SAD-0.6-1.2. Metering hopper of aerodynamic dryer is a welded construction with an integrated screw conveyor and an agitator and is a reservoir for raw material supplied to the dryer. From metering hopper crushed wood chips get through a screw feed into a dryer. Rapid flow of hot air in a dryer keeps raw material in suspension. Air in a dryer is heated by a heat generator operated on solid fuel. Heat generator is a welded construction in the form of furnace with a combustion chamber internally isolated by fire bricks, thermal flash suppressor and air plenum chamber. Since air flow rate is very high and materials are right in the flow, heat exchange between air and material is very high. In the process of drying, pure cold air is heated by heat generator and mixed with wet material whereby wet sawdust is dried in few seconds. Further, dry materials are run through a fan and cyclone, and exhaust air is discharged into atmosphere.

The third and final stage of briquetting: Pressing by hit-mechanic presses.

At this stage prepared material with particle size up to 7 mm and humidity of 12.8% gets in press metering hopper through a drier steam separator. Metering hopper of briquetting press is a welded construction with an integrated screw conveyor and an agitator and is a reservoir for raw material. Recycled material is supplied through horizontal and vertical screw conveyors to working chamber located in front of a plunger pump. Plunger pump of a hit-mechanic press is horizontal. Its operating pressure is 1,400 kg/cm. Pressure-lubricating system ensures low wear of parts in the process of workloads. After being pressed, briquettes are pushed through removal mechanism (conveyor) which protects briquettes from premature mechanical action and provides access when necessary. Mechanism design also provides a visual control of briquetting process.

In conclusion, let’s list the advantages of hit-mechanic briquetting method.

Advantages of a hit-mechanic press:

While developing a press our team paid special attention to such important requirements as: