1.1 Introduction
Nigeria is an agricultural nation. Melon (Citrullus Vulgaris) is widely cultivated in Nigeria, among other seedlings during the planting season yearly. Several tones of the melon seeds are gathered each harvesting period but only very low percentage of the total harvest are dried by atmospheric draught and bagged for storage. High percentage waste is encored due to lack of good processing and storage facilities.
Melon when properly processed yields a lot of by-products, which could be used as food or as raw material for small and large scale industrial manufacture melon is highly enriched with oil. It has about 45% oil content. The oil could be extracted to form a very good source of vegetable oil.
After pressing out the oil, the remaining product can be used as food for human of as an additive in agro-feed manufacture. Melon without oil can be grounded and used as thickener or binder in the chemical and pharmaceutical industries.
The outside shell of the melon seeds when properly harvested in large quantity can equally be used in preparation of agric feed. The shell has about (12-55) MJ/kg calorific value and therefore can be used as a source of energy for industrial use.
The major problems encountered in the processing of melon seeds are the removal of the yellow outside shell and the separation of the broken shells form the white seeds. Locally as at now, manual approach is used for the de-husking and separation. The consequence of this is low productivity, increase in processing time, and increase in human labour.
A mechanized method of de — husking and separation will definitely increase productivity, reduce processing time and bring down human labour input to the minimum.
These problems arising form the manual de-husking and separation of the melon white seed from the shell necessitated the idea of designing, constructing and testing a melon de-husking and separation machine for our local communities and industries.
1.2 Description of the Designed Melon
De-Husking and Separation Machine
The assembly drawing of the designed de-husking and separation is shown in appendix.
The machine consists of the following components namely.
- Impeller
- Inlet hopper
- De-husking casing
- Inlet channel
- Casing cover
- Chequer linings
- Exit channel
- Adapter
- Blower
- Electric Motor
- Structural Stand
- Blower Casing
- Blower Impeller
- Blower Casing Cover
- Blower Suction Channel
- Air exit channel
- Blower mounting base
- Flange bearings
- Bolts and Nuts
- Blower shaft
The de-husking impeller is housed by the de-husking casing. The casing is lined with cylindrical chequers. The cylindrical impeller is mounted very closely to the inside walls of the cylindrical casing leaving a minimal gap to contain the melon seeds as they flow through this gap from inlet channel to the exit channel. The casing is covered with a cover plate. The impeller is connected to the shaft of the electric motor through an adapter. The blower impeller is housed by the blower casing. The blower sucks air from outside through the suction channel and the impeller forces the air through exist channel as required. All the arrangements of the machine are carried by the structural base. Bolts and nuts are used to ensure proper mounting of components on the structural base.
1.3 Principles of Operation
The principle used by this machine to achieve the melon de-husking is attrition and density differential between the cracked shells and the white seeds is applied to achieve the required separation.
The electric motor provides the primary motion which rotates the de-husking impeller. The melons are introduced through the inlet hopper of gravity. The melons are directed to flow towards the walls of the casing to the chequers. The rotating impeller then rub the melons on the chequers in the direction of rotation of the impeller. The melon must be properly treated with water (moisture) arieated properly before de-husking.
The rubbing action peels the shells of the melons and equally move them along with the broken shells in the direction of rotation to the exit channel.
The blower shaft transmits motion from the electric motor to the blower impeller, thereby delivering certain quantity of air which is channel to meet the broken shells and white seeds coming out from the de-husking casing.
The broken shells being lighter than the white seeds are carried away by the air to a different direction while the white seeds move into a receiver where they are collected.
1.4 Advantages
- The machine combines two processes in one ie de-Husking and separation.
- The machine is portable and occupies very little space.
- The machine is cheap when constructed locally, compared to cost of importation.
- The machine can be confidently be driven by a single phase electric motor thereby making power consumption rate very low.
- De-husking and separation time is highly reduced by using this machine.
- Labour input in de-husking and separation is also drastically reduced.
- Productivity in de-husking and separation is highly increased.
1.5 Objectives of Study
- The objective of this project is to design, fabricate and test a melon de-husking and separation machine in order to increase productivity in melon processing and reduce human labour of manual de-husking and separation to the bearest minimum.
- This project will improve the living standard of million of rural dweller who may engage in melon processing.
- It will encourage the growth of small and medium scale industrial enterprise in the agric — processing nation wide.
- This project will contribute to the overall economic development of the nation by encouraging indigenous engineers technologists and technicians in designing, fabricating and testing of processing machines.
1.6 Scope of Study
This machine only handles treated melon. The designed machine is expected to de-husk and separate about 450 kg of melon in an hours work. This is result in about 3, 600kg or 3.6 tonnes in eight (8) hours work.
1.7 Beneficiaries
- The major beneficiaries of this project are rural dweller who might engage themselves in melon processing.
- Small, and medium scale agro-industrial set up who produce products like vegetable oil and food items.
- Chemical and pharmaceutical industries who might be using extracts from melon as binders, thickeners for drugs etc.
- Agro — feed industries who might be using melon as additive in feed production.
