Construction of any part or structure is the joining of many sub-parts into one main structure. In a biogas plant, construction is the most critical part of the making of a project because it entails the actualization of the idea to be a tangible project. Biogas plant construction is comprised of many activities, all interlinked into one major activity. This section covers the following areas: Biogas construction considerations, biogas plant construction materials, and biogas key construction parameters.
Biogas construction considerations
- Studying the materials for construction of the biogas site together with their acceptable standards.
- Planning the biogas layout, where the steps are explained and the methodology for the construction of the biogas plant is illustrated.
- Project installation and implementation: The actual construction of the biogas plant takes place according to a well-laid-out plan.
Biogas Plant Construction Materials
In the construction of a biogas plant, one needs to be adequately prepared with the right materials. The following materials and equipment are required for the construction of a 24 m3 fixed-dome biogas digester:
Construction blocks (1000 pcs), Cement (100 Bags), Ballast (10 tonnes), Sand (20 tonnes), Dust (15 tonnes), Waterproof material (20kgs), Y8 (20 pieces), Y6 (8 pieces), Plywood (10 pieces), Nails (8kgs), Wire (6kgs), Pipes (5 pieces), Pipings and fittings, Gas Filter (4 Pieces), and Gas Burner (4 Pieces)
During the installation of biogas systems, the biodigester, gasholder, expansion chamber, piping network, gas utilization, and effluent treatment units are all installed (Bensah, Antwi, Ahiekpor, May 2021).
Some of the specifics about some of the construction materials are described below:
Sand
Construction sand should be clean and free of soil and organic elements. The building will be seriously impacted by dirty sand. Fine sand should be used for plastering while coarse and granular sands should be utilized for concreting. Dusty sand should be avoided at all costs.
Cement
A project developer should seek out high-quality cement from a renowned cement manufacturer. It’s best to keep the cement away from any walls. The cement should be free of lumps. If there are any small lumps, they should be easily breakable with your fingers.
Bricks
Bricks should be of good quality, made in the size of 23cm by 11cm by 7cm. The brick should be well burnt, straight, and regular in shape and size.
Gravel/ Ballast
Gravel should not be too large or too little. Clean, firm, and angular gravel should be used. If it is soiled, it should be cleaned first. It is also a good idea to filter out the ballast.
Pipes
Pipe selection is important to avoid damage that could lead to gas leakage and to extend the system’s life. Because of their endurance and corrosion resistance, galvanized pipes are perfect. Cost, on the other hand, must be considered. Good-quality PVC pipes can also be used.
All fittings, such as bends, valves, and meters, must be securely sealed to prevent leakages. Teflon tapes can be used to adequately seal connections in PVC pipes. Use excellent adhesives and Teflon tapes while working with galvanized iron (GI) pipes (Bensah, et al., May 2021).
Paint
Paint is required for the biogas construction. The paint is used to mark points as the construction of the biogas continues. Moreover, it is used in giving the biogas plant a colorful taste. Different types of paint may be used. However, care must be taken in ensuring that the paint does not mix with the slurry as it may lower the quality of the biogas plant. The paint selected should be from a reputable company.
Water
Water is a crucial element in biogas construction as well as its production. Water must be clean and free from impurities and should not be salty. The water should be of a considerable volume, say 1000 litres, as much will be used to mix cement and curation of walls. Water is available at many places for construction. Wherever it is available, the irrigation canal water or the groundwater accumulating in the digester bottom is used for construction and curing. It is the piped water that is used in other cases. Engineers and masons use the piped water for the initial feeding of dung and also use the same for the daily operation of the biogas plant (Sangha, 2013).
Biogas Plant Construction Parameters
The Reference Line
All vertical measurements are collected from a reference line, which is a thin rope connecting two leveled spots running through the center of a biogas facility. It’s a good idea to mark the level of the reference line on a tree or a building near the plant so you don’t lose it. The reference line for slope setting should be along a contour or across the slope.
The Radius Stick
This is a guide stick that is used to manage the radius of the digester and keep the bricks in a spherical shape when they are being built. This gives the distance from the radius point to the hemispherical digester’s inner wall. The radius stick end can be secured with binding wire or manila rope and can spin around a nail or an iron bar.
How to make a radius stick
A nail along the length of a piece of wood can be used to indicate the radius of the digester. Steel or bamboo can also be utilized as an alternative. The radius stick’s purpose is to ensure that all blocks and bricks rotate around a particular radius, resulting in a round, dome shape.
In the bricklaying process, the radius is a highly useful instrument. It’s used to make sure each brick is laid properly. This is accomplished by ensuring that every stacked brick is aligned with the radius. When the rod is placed on the center pillar, it should be able to move about freely.
A biogas radius and construction plan.
Conclusion
Construction of the biogas plant is very crucial. This is where the infrastructure of the biogas plant is laid out. A biogas plant must be constructed accurately as per planning and measurements. Integrity must be observed during construction. The construction materials must be proper, pure, and perfect for a steady structure to be installed. Therefore, according to the insight given in this article, a person will gain the know-how in how a biogas plant is expected to be constructed.
References
Edem Bensah, Edward Antwi, Julius Ahiekpor, (May 2021). Guide For The Design And Construction Of Fixed-Dome Biodigester. Retrieved from https://www.researchgate.net/publication/351818542
SKG Sangha (January 2013) Biogas Plant Construction Manual. Retrieved from https://www.build-a-biogas-plant.com/PDF/SKGConstrution%20manual2013.pdf
Acknowledgment
This article is an excerpt from the book “The Blue Flame: Biogas Training Blueprint”
Suggested Citation in APA
Wanjohi, A.M. (2022). The Blue Flame: Biogas Training Blueprint. Nairobi: Kenya Projects Organization
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