Design of a sawdust pelleting machine

Abstract

This paper seeks to carry out the design of a pelleting machine with a capacity of 900kg per hour for the Company X. Apparently the boilers at the plant are using wood chips, a by-product from the milling operations as their source of fuel but off late the plant has been experiencing a serious fuel shortage. The fuel crisis emanated from low plant availability caused by old and dilapidated machinery. Major breakdowns that brings the plant to a halt for long hours are abrupt and rampant and during that time no wood chips are produced resulting in a fuel shortage. Following this fuel shortage the boiler operators have resorted to rationing the fuel input into the boiler as it has to run continuously regardless of whether the plant is moving or not. This rationing has resulted in poor boiler performance and low efficiency which has in turn affected the timber drying kilns. The boilers are producing poor quality steam which has had the effect of doubling the timber drying cycles. As a result of doubled timber drying cycles half of the timber produced is sold as wet off sawn at a relatively low price which is a loss to the company. The management and the engineering team in a bid to do away with this problem proposed the use of sawdust as additional boiler fuel. After a consideration of the type of boiler fire grates at the plant it was found that raw sawdust cannot be used as it has a tendency of choking the grates blowing out combustion so it has to be pelletized. With this problem at hand this project zeroed in at the design and development of a pelleting machine that will specifically meet the pellets need at the wattle company. Literature review was done on several types of pelleting machines’ operating mechanisms and from this literature three possible concepts were generated. These concepts were evaluated and the best was chosen and developed into a finished design ready for fabrication with all working drawings available for each component. The machine was designed with a constraint budget of USD $10 000 and it will provide a backup and additional boiler fuel to the already being used wood chips.