Up- Scaling Biogas for Sustainable Development and Mitigating Climate Change in Sri Lanka. Construction Guide for Srilak Umaga Fibre Dome Biogas Unit

Transcription

1 Up- Scaling Biogas for Sustainable Developent and Mitigating Cliate Change in Sri Lanka 6 Construction Guide for Srilak Uaga Fibre Doe Biogas Unit

2 Table of Contents 6.1 About the Sirilak Uaga Biogas Unit Layout Excavation Laying of Foundation Preparing, fixing fibre ould for concreting Connecting of inlet Sealing of edge of the Digester and fibre glass shell Curing of the unit Evaluation Annexures: Annexure Annexures 02 and Annexure Annexures

3 UP- SCALING BIOGAS FOR SUSTAINABLE DEVELOPMENT AND MITIGATING CLIMATE CHANGE IN SRI LANKA 6.1 About the Sirilak Uaga Biogas Unit The body of the text is in Cabria size 12, justified and British English. Spacing after paragraphs is 6 pts and line spacing at It is recoended for each subtitle to start on a new page. Iages as seen below ust be foratted as follows: Wrap text: top and botto. Please add a caption with the title Iage at the botto of the iage and centre alignent. Figures ust be captioned with the title Figure. By using this Sirilak uaga technology Eng. Rohitha Ananda did soe research to construct doestic type biogas unit without brick and ceent. Because of the saller in size it is difficult to access and do the plastering inside of the unit so for the easy construction purpose he did fibreglass ould which can construct with concrete and it can use for doestic purpose such as 2.53 in size. Now he did fibreglass oulds for 2.5 3, 43 and 6.53 biogas units. By that ould it reduces construction tie and by that reduces cost for construction. He ade fibreglass ould to construct the unit with concrete and for gas chaber he use fibre shell to prevent gas leakage. So it was succeed and now ore than 10 units constructed this low cost ethod. As another advantage fro this ethod is use of concrete so the three roots can t daage the digester because of that it will last for ore than 40-50years. Iage 1 Difference between earlier Plug flow type and Sirilak Uaga type fro appearance

4 6.2 Layout After the selection of suitable area, it can ark with the diensions of the biogas unit in line with the design requireents. (refer 3 rd booklet for do the lay outing) LTOP wtop LTOP=LBase+2 x h x slope Figure 1 Lay out plan for the unit This slope can be vary according to the soil condition of the site 1 Iage 2 Marking layout using pegs and threads 1 Annexures ust be added to through a footnote.

5 6.3 Excavation The walls of excavation can have soe slope according to the soil condition of the site. If it is hard soil it can excavate with vertical walls. Taking the internal diensions (length in L0 and width in w0) and the wall thickness (t) into consideration, botto diensions of the pit is: LBase= L0+2t+0.5 wbase= w0+2t+0.5 (For the setting of outer part of the ould and easy reoving it should keep about 0.5 clearance) 2 Height length and width of the excavation for unit is shown in Figure 2 LTOP w h LBase Figure 2 Diensions for excavation 2 W0, L0, h and other values for the biogas unit please refer the annex 4

6 6.4 Laying of Foundation Iage 3 After excavation of the pit using excavator In this ethod also laying of foundation ay vary depending on varying soil bearing capacity & ground water levels to prevent the structure getting disturbed. First step in construction is foundation lying. So according to condition of soil, it can use stone asonry work(6 x4 ) in 6 height and after it can do concreting 1: 2: 4 (ceent: sand: etal grade 20),100 thick with reinforceent of 10 tor steel in 200x200 for soft soil. For the ediu soil condition base concrete should be 75 thick in grade 20 with reinforceent of 10 tor steel in 200x200. Then it is a hard soil it can use 1: 2: 4 (ceent: sand: etal grade 20) concrete in 75 height and it is no need to do the reinforceent due to hard soil. After the laying of foundation leave it to settle for 1 day. However, if the ground water level is high, the bed concrete has to be reinforced ade out of 10 diaeter tor iron rods as per the picture.

7 Iage 4 Reinforceent for the base concrete Iage 5 Laying concrete with reinforceent as a foundation for the unit 6.5 Preparing, fixing fibre ould for concreting After laying foundation it should keep for 24hrs as a standard for strength but when start the construction we can t wait for that uch of tie and keep it for about 6 hrs and restart the work. Until it gets strong it can prepare the ould by applying non sticking liquid or ould oil like engine oil or paint. For reduce the cost it can use burnt engine oil for the applying purpose.

8 Iage 6 Applying engine oil in the ould After applying oil in all parts of the ould it can start fixing of ould on the foundation (4-6hrs after lying of foundation). As first step it can do fixing of inner part of the ould and after the outer parts. Below pictures show the process of fixing ould.

9 Iage 7 Fixing of Fibre ould inner and outer parts After fixing of this ould it can t bend or defor when it fills concrete. So it needs to hold strongly, to aintain the rigidness it should give proper support by tiber or baboo to withstand when it fills and copacting of concrete. To aintain the gap of 5 between inner and outer oulds it should use spacers. Iage 8 Wooden and baboo supports fixed for preventing deforations.

10 6.6 Connecting of inlet After fixing of the ould it can insert the inlet pipe to the unit. Iage 9 Fixing of inlet pipe to the digester Now well- fixed ould is ready to concrete. For the concreting purpose we use grade 25 Ceent concrete 1 : 11/2 : 3 ixed with water proofing aterial(pudlo ceent) for the filling of the ould. But to get the good finish and good bonding while preventing leakage the ixture for the filling changed as 1 : 0.75 : 0.75 : 1.5 : 1.5 ceent : sand : etal dust : etal(3/4 ) : chip stone(2). And it needs to add Padlow ceent (1kg for 50kg bag) as well for preventing water and gas leakages. Also don t forget to copact the concrete well with vibrator or the iron rod. Iage 10 After filling concrete to the ould

11 Then after the fibre glass doe place on top of the concreted tank with soe ceent or concrete paste. Fro the inside of the doe also need to place ceent or concrete paste to prevent leakages. Then outside fibre parts of the doe area and outlet tank should fix and support with wooden or baboo sticks to prevent deforations when concreting. Iage 11 Fixing of gas chaber and the fibre ould Now it can start filling concrete in fibreglass gas chaber and outlet tank. Iage 12 After finishing the biogas unit For the concreting of the above entioned doe and out let parts, it can use sae ixture of concrete.

12 6.7 Sealing of edge of the Digester and fibre glass shell To create the anaerobic condition inside the digester, the biogas digester it should be water- tight and air- tight. The concrete walls and fibreglass doe ust be sealing with ceent and water ixed with sealing copound (eg: Chefix). For the ixture sealing copound add 1-2% of the ceent you use. After the sealing it can apply ceent- sealing copound in the all wall area twice in the cross directions (90 0 ) by that it can be ake sure the sealing of whole wall area of the digester. Iage 13 Sealing of concrete walls and fibreglass doe As a last step after one day it can reove all the supports and the ould parts. As soon it reove the ould, see whether there are any visual defects like honey cobs if presence it can be repair by pasting ceent sealing copound ixer. 6.8 Curing of the unit After copleting of the construction work it needs to keep one or two days to cure the unit. So use any curing ethod for cure. As a coon ethod it can use wetted blanket ethod if it directly explore to the sun or if it in shady area it can wet with the water after soe ties. 6.9 Evaluation The quality of digester should be checked before starting operation. The ain point to be easured is water- tightness and air- tightness. First of all, go inside the digester and check all the parts for cracks and holes. After visual check water- tightness and air- tightness should continue. After the successful copletion of above testing s it can start the filling of inoculus (such as cow dung). After few days it will produce biogas.

13 Annexures: Annexure 01 Description Slope(Height : width) Sandy soil 1 : 1 Sub- sandy soil 1 : 0.67 Sub- stick clay 1 : 0.50 Clay 1 : 0.33 Soil with gravels or cobbles 1 : 0.67 Dry loose 1 : 1 Annexures 02 and 03 Drawings of the Biogas units 63 and 83 Annexure 04 Sl. No. Total volue 3 (v1+v2+v3) Digester Diaeter (D0) Doe Height (f1) Base depth f1) Wall height (H0) Doe Radius (R1) Base Radiu (R2) Outlet diaeter (d0) Outlet Height (ho) Total Height (f1+f2+h0) Annexures 05 BOQ for 6 3 and 8 3