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Last edited 24 Oct 2022

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Wood pellet processing plant

1 Introduction
2 Process
3 Renewable
4 Related articles on Designing Buildings

[edit] Introduction

Wood pellet plants combine the complete procedure of biomass particle production, including all processes from drying out to squashing, granulation, cooling, testing and packaging. Plant may be arranged or customised in a variety of ways according to need as well as the degree of automation in cooling, packaging, and feeding.

[edit] Process

Appropriate raw materials are selected for natural fibres such as logs, branches, sawdust, rice husks, etc. These enter by conveyor belt and are sent to the wood hammer mill. On leaving in a crushed form these are directly send onward by the screw conveyor. This leads into the drum, similar to a clothes dryer, where materials are mixed with hot air. The dried material is accumulated by a cyclone separator, and then exits from the bottom of the airlock.

The next stage is the conditioner which is entered again via the screw conveyor, this conditions the material to the ideal level. Once achieving the intended moisture level the material is sent to the pelletising chamber, this performs a granulation process, with the material exiting as small round pellets of 2-12mm. The pellets then enter the cooler, drying the pellets to below 10%, and also cooling them to a regular temperature.

The remaining powder passes through the rotary category screener, which can separate out unqualified materials and granulate these once again. The screened pellets are loaded by an automated weighing device and then sealed by an automatic stitching device.

The complete set that makes up a wood pellet plant is not just timber pellet production equipment, it also a variety other treatment equipment according to the sort of resources and humidity.

If the raw materials arrives in larger sizes such as whole branches, it needs to be crushed into timber chips less than 5mm by a separate crusher, if it arrives smaller it can enter directly. If the humidity of the raw material is 15%-20%, it can enter the device directly, if it is higher than 20%, it has to be dried to 15-20% prior to granulation.

[edit] Renewable

As a renewable fuel, timber pellets have several advantages, such as high calorific worth, reduced emissions, huge particle proportion or compression after moulding, small volume, and combustion resistance. They have a higher level of processing than wood chips but due to their form can often be used more easily in small and large automated heaters, from industry to individual homes as an alternative fuel. Wood pellets can also utilise wood waste from saw mills and carpentry workshops.

Making use of wood pellets as a fuel is a realistic alternative environmental power resource that can help reduce carbon emissions, and has been used both in rural and urban locations.