KENBIM DOMESTIC BIOGAS CONSTRUCTION TRAINING
Contents
1. KENBIM DOMESTIC BIOGAS CONSTRUCTION TRAINING TABLE OF CONTENTS i Chapter 1 introd ction sensenta n eee Ried set Dru ut vt ela eacus sev eceadaieees a Need to traihitdsons i oe te teen RR totae edet et b Why weneed totrain masohszso in ect eret tese reiecit EU C Objectives of the Biogas Mason Training BMT ccsscssssecessessssssscsscsecsecsesessessessessesseseecsesaecaeeaes ds Expected Outputs neret iret tedio tess ORI E a e History of biogasn the co ntry tete oe nee d intet ette ete ite etus f Biogas Technology History and its development in Kenya sese g Biogas Programme objectives and targets sss sese nennen nnn nnn tn tnnt nnn inns n ns ii Chapter 2 size selection iet t Ir Deiner AN pecca a Guideline for the selection of the proper size of the biogas plant sse b Looking for client personal information essei esee eene tnn nhanh ntn th staat tetas taire ranas c Selection of appropriate size of Biogas Plant based upon dung availability sss d Chapter 3 site selectioH oreet teer ee isaac ahe hanes e Sitesselection for BGR sro ede i ott ttp RE t Dicen ORE f Cowshed or Pigsties s t red ie Rt te a eet ae AS iii Chapter A CONSTRUCTION uo eoe tee e a i e een e E Ee aL Shoat a Types and quality standards of construction materials eese seen en2. Example of some Biogas consumption rates in various applications Cooking Between 150 250 Its of biogas are used in 1 hour for boiling 1 liter of water depending on the efficiency of the burner Lighting Between 120 180 Its of biogas are used in 1 hour a biogas lamp produce light equivalent to a 75 watts bulb Heating and industrial burners Between 450 500 Its of biogas is used per one hour Refrigeration Refrigerators with 100 Its capacity can run on between 30 80 Its of biogas per hour Engines Motive power 420 Its of biogas can be used in 1 hour To produce electricity of 1kWh 700 Its of biogas is required CHAPTER 7 OPERATION OF THE BIOGAS PLANT Filling up of the digester with feedstock The initial feeding of digester is done immediately after 21 days from the last layer of plastering cow dung should be collected before and during the construction of the biogas plant While filling the digester make sure that the cow dung is clean without containing sand trash wood grass household waste goat sheep droppings and other impurities Such materials will enter the digester and form a scum layer blocking the gas to rise and enter the gas holder The dung is mixed with urine and water at the ratio of 1 1 While mixing cow dung with water remove all the unwanted material mentioned above The digester is filled daily with the quantity of cow dung and water described to have maximum ga
3. Number of people who are to be served Number of people or animals determines the amount of organic material available for feeding the plant daily Animal rearing system Slurry use discharge The size of the farm for slurry use Hygienic and sanitation conditions to be achieved Biogas plant costs affordability by the client d kS kS P P t e efe KS kS Selection of appropriate size of Biogas Plant based upon dung availability Considering many factors already discussed at this point it is easy to decide the size of the biogas plant to be installed domestic biogas plants standards 4m 6m 8m 10 m or 12m3 the quantity of daily feeding materials and the pre determined hydraulic retention time HRT of 60 days will eventually guide the digester volume CHAPTER 3 SITE SELECTION Sites selection for BGP Site should be convenient as possible to feed the digester Consider existing structures at the Site and how they can be incorporated in the biogas system e g cowshed kitchen stove etc Consider the terrain ground level the existing natural slope if it allows slurry to flow by gravity A level ground will have a different approach from a ground with a defined slope Where there is no slope the slurry will be considered for drying or composting Consider infrastructures around the site like roads pipeline rivers rocks obstacles like big trees etc Consider the
4. fee Construction fee Guarantee amp after sales service 1 yr Grand total NOTES The value of material available on site is e e HLHnBOH HDpOinuDsb snrmi PF 2 RYN BRP RP RP RP RP PR kg length length pcs pcs pcs pcs pcs pcs pcs pcs pcs pcs pcs pcs pcs pcs pcs pcs pcs pcs pcs pcs pcs pcs l s l s l s Oo somoogocouocosomo D Date witnessed sese ROLES OF MASON The masons will be responsible for identifying the client Initial site visit to determine the feasibility for biogas plant The masons are responsible for filling and sign contract and bill of quantity BOQ Proper lay out of site for excavation Supervising site preparation and standard of quality of materials Construction and installation Inform the client about proper feeding and operation of the biogas plant and appliances Filling and signing of the plant completion report Provision of after sale service Report to supervisor any problems that need the domestic biogas programme support ROLES OF SUPERVISOR Ensure quality construction by regular site visits Counter sign the plant completion report To respond to the request from a mason to assistance Advise assist masons on proper filling of different forms Promoting domestic bi
5. measuring tape thread machine main gas valve wire brush pipe wrench screw driver and oil can Plastering of the upper part of the digester gas storage The outside upper part of the digester is plastered first using similar ratio as the lower part After installing the gas outlet pipe plastering of the gas storage area inside the digester starts in the following sequence 7 coats to be applied 1 Wall washing using cement water 2 Plastering 1 centimeter cement sand 1 2 5 3 Wall washing with cement water 4 Plastering 1 centimeter cement lime sand 1 74 2 5 including water proof cement at 2 kg per 1 bag of cement 5 Wall washing with cement water water proof cement ratio as above 6 Plastering cement sand 1 2 5 the cement with a mixture of water proof cement ratio as above T A paste of cement cement screed or neru water proof cement as above Sand for use in the gas tight plasters should be well sieved and it should not contain any dust dirt The 2 4 and 3 plasters have to be done consecutively in not less than 48 hours from one another After the plant construction work floor work and plastering the plant is supposed to be in moist condition in order to allow curing to take place The plant will be ready for initial filling 2 weeks after finishing the final plastering Expansion compensating chamber construction The function of the expansion chamber is to store the digested slurry and for this matter to develop p
6. 3 inimum 140 cm No housing chamber is required i Incase of problems the customer can easily help himself ii Only made out of standard fittings iii No block sensitive against surface water and erosion iv Less digging work during installation v Less material required NB The installation requires careful planning especially if the max pressure of the plant is not standardized CHAPTER 6 FINISHING WORKS Finishing works Fabrication of all chamber and manhole lids o The lids should take the shape of the intended opening o The size of the lid must be flush with the outside wall of the intended opening o The thickness of the lid must be at least 7cm The following steps are for fabrication of the lids Step 1 Set the base out of plastic or used cement bags on a flat ground Step 2 Use Bricks or a mould can be used to make the desired shape Step 3 Use Welded mesh resting on small stones is used as the reinforcement and 8mm round bars are used to make the handles The handles are fixed to the weld mesh using a binding wire The lengths of the handles is about 8cm 16 Step 4 Mix Strong mortar in the ratio of 1 3 cement sand Step 5 Pour Strong mortar in the mould and allow setting for 7 days Cleaning inside the digester and expansion chamber Landscaping Make the place look attractive e g plant flowers or grass Clean all the tools and equipments used Propose the improvement of the cow shed to the farmer if n
7. Open the water drain valve to remove any water condensed inside Purchase better stove In case of lamp does not give bright light Dirty glass screen Cracked or destroyed mantle Incorrect gas air mixing ratio Presence of water in the system Blockage of the mantle holder hole Clean the lamps glass screen regularly Replace the cracked mantle Adjust the primary air knob in order to get the right mixture Open water drain valve to remove any water Clean the mantle holder hole Maximum gas pressure achieved but still gas quantity is not as expected Under feeding or irregular feeding Scum formation inside the digester Ensure that daily feeding is done in sufficient quantity Ensure that mixing is done properly and all the unwanted material are removed Empty the plant remove the scum and stir the inside slurry No any gas reaching the appliances Water has blocked the gas passage along the pipe line No any gas being produced inside the digester Disconnected gas pipe line Inhibiting substances have entered into the digester Closed main gas valve at the Check for the presence of water along the gas line and drain it Check for gas leakages in the pipe line and solve them Check for any pipe disconnection and reconnect it Check the main gas valve and reopen it Remove the inhibiting substances or 21 test unit chamber chemicals from the
8. routine sprinkling of water needs to be done during 5 to 7 days Fixation of dome gas pipe Note Fixation of dome gas pipe is done before plastering inside of the digester Step 1 Thread one end of a piece of galvanized pipe of 1 1 5 inch and a length of 41 cm and mount a T joint It is advisable to grease the thread in advance to prevent corrosion Step 2 Weld a disc and some scrap pieces of iron bar 4 cm on the other end of the galvanized pipe Step 3 Join the other components of the testing unit to the galvanized pipe Step 4 Provide temporary support below the testing unit Step 5 Position the pipe with the testing unit side above on top of the digester See diagram Step 6 Reinforce with concrete of the mixture 1 3 3 including 2 of water proof cement Step 7 Place main gas valve on the test unit The disc prevents gas from escaping along the pipe wall and iron bars act as an anchor and gives additional strength to the pipe fixed in the brickwork Under normal operation the T joints should remain sealed and closed with plugs and all threads are joined with seal thread tapes which as a rule of thumb should be applied in approximately eight turns The test unit chamber is where gas leakage testing measuring of gas pressure in the digester and gas flow consumption rate is normally conducted and from this place pipes are laid and connected direct to the consumption point Tools Grease Seal tape portable pipe vice hacksaw wheel cut
9. ar R8 lengths 111 1 1 1 9 Weld mesh heavy gauge Pcs 1 1 2 2 2 10 Binding wire Kg 1 1 1 1 1 Sub Total 1 B Piping fittings Assorted items C Labour cost D Excavation amp site preparation E After sales service amp Guarantee 1 yr GRAND TOTAL KENBIM Domestic Biogas Plant installation Bill of Quantities amp Pricing Ngugi Kimwaki 1 Construction Materials QTY UNIT RATE Household Mason Co 1 0 Cement 50 kg 17 bags 1 1 Water proof cement 1kg 4 bags 1 2 Quarry stones dressed 6X9 0 5 lorry 1 3 Bricks 230x110x70mm 200 pcs 1 4 River Sand 0 5 lorry 1 5 Ballast 1 tonnes 1 6 Ballast chips 1 4 1 tonnes 1 7 Lime 25kg bags 25 kgs 1 8 Binding wire 2 kg 1 9 Timber 2 x2 2 1 m 1 10 Plywood 3mm 1 sheets 1 11 Nails 3 0 5 kg 23 1 12 1 13 1 16 1 17 2 1 2 2 2 7 2 8 2 9 2 10 2 11 2 12 2 13 2 14 2 15 2 16 2 17 2 18 2 19 2 20 2 21 2 22 2 23 2 24 2 25 3 1 4 1 4 2 Nails 2 GI pipe 3 4 PVC Pipe 4 Sanitation welded sq mesh G8 Piping Materials Dome pipe 3 4 410mm GI Ballcork 3 4 Biogas Lamp Burner Single Burner Double Pressure manometer PVC pipes 3 4 PVC T joint PVC Reducer 3 4 x1 2 PVC Pipes 1 2 GI Elbows 3 4 PVC Elbows 1 2 Reducer 1 x3 4 Hexagonal nipples 3 4 PVC Socket 3 4 GI T joint 1 2 GI Socket 3 4 Hexagonal nipples 1 2 GI Reducer 1 x3 4 Tangit glue 50ml GI Ballcork 1 2 Labour Excavation amp site preparation Company services amp
10. art of the digester gas storage sse v Expansion compensating chamber u sscesevsssescsevesescssesessesessnscsesessessesesesssscstesssessesessescasenssssteseneessaees w Construction of Mixing Chamber scesssssesseesesssesssssesessecessssssssesseasessssssessessecessaeseneessessesaseseeseasenseess iv GHA Pte eS Ii Dis ost ete nte Dee eiae esee a Re gets a Fixation of pipeline alignment and digging of trench sees ene rn nne tn nhn tanen nnn b WTOP ENDS sott entia E v Chapter 6 finishing works senasis nne ana tente tetntnn th sesssesuesuscascassessesseseeaesaeaseesees Indoor PID IAG aca eet eredi t pitt a Sa EE Checking for leakages i oen eh tn epa rn is Function of test unit chamber uu sccessessessessesccesesseessssesssessssecessassssesseaseasessessssssessscasssscasseaseaseaseaseaasesseass Some new technologies and modification of gas appliances esses eese eene tnnt nnn n rnntn nennen GS TET Ao or rTTE f Example of some biogas consumption rates in various applications eese eese eene vi Chapter 7 operation of the biogas plant esses sese teten nnne nntn ntn ntn trs tasse testen irgend nna a Filling up of the digester with feedstock scsscsssssssssssecessessessessessenssesessssssessssaessecassessesseaseaseasecsesaseessess vii Chapter 8 slurry utilization sess eene nnne nnne nent ntn ntn ntn shs nas siste sa natas
11. bricks on the slurry outlet allowing space to pass in and out Step 2 prepare a radius stick of dome radius as in drawing and fix to the centre pipe the opposite end should have a nail fixed at 90 to the stick Step 3 lay mortar on the wall and shape to assume the dome shape according to the radius stick Lay the bricks on the mortar bed one by one making sure each brick is at right angle to the stick Step 4 continue similarly making sure that the next course starts 1 brick away and hooking of brick is done whenever instability is noticed in setting Continue similarly until bricks close to a dome Step 5 before closing the brickwork install the dome gas pipe and support as necessary See below Tools Radius stick spade brick trowel bucket hoe wheel barrow measuring boxes and hooks Plastering the digester wall At the inside of the digester plaster with ratio of 1 74 4 with a depth of 2cm and wall should be washed with cement water before plastering Backfilling lower part Soil backfilling and compaction around the lower part of the digester should be done up to 3 courses lower Compaction is done between 30 60cm and water is added to bring more compaction Soil compaction is important and it must be properly done because once the digester is in use the block brick wall is subjected to high pressure from inside and therefore it must be supported from the outside Curing of wall To avoid cracking and encourage binding
12. ch are the responsibilities of the mason Why we need to train masons This handbook is designed for the mason who wants to make a living out of building biogas digesters For biogas technology to perform well a guided approach is needed to achieve this disseminate build and sell the technology We are training masons so that they know how to build a bio digester and to standardize the bio digester so people can use the same sizes criteria The objectives of the Training are streamlined in this manual as follows 8 To build technical capacity to groups of artisans technicians so that they get involved in the construction of biogas plants for their own income generation and faster biogas promotion and dissemination in the country b To strength KENDBIP s capacity for promoting domestic biogas plants in many regions of Kenya c We expect the masons to train the end user how to operate and maintain the Biogas plant Expected Outputs At the end of the training all participants gt To be familiar with the domestic biogas program in the country gt To acquire detailed knowledge on biogas technology its importance and use of biogas plant products biogas and bio slurry gt To have the required skills to be able to construct domestic biogas plants ability to plan set out and construct through Reading biogas plant drawing Selection of appropriate plant size construction sites and materials Advice and make contract with client
13. digester The feeding materials not entering into the digester Blocked inlet pipe Position of the inlet mixing chamber placed below the overflow point Poke through the inlet pipe Ensure right vertical dimensions are used to avoid wrong placement of the mixing chamber Bio effluent too thick at the overflow Incorrect dung water mixing ratio less water urine No hydraulic movement inside the digester Water leakage on the lower part of the digester Water leakage at the expansion chamber base Ensure good mixing consistency at feeding Check for water leakages inside the plant and expansion chamber and seal them off Make sure that the gas is used daily to allow hydraulic movement to take place inside the digester Empty the plant and seal the cracks or renew the base Slurry entering the gas pipe line Gas outlet pipe placed below the over flow point check slurry overflow point if it is not or was blocked reduce slurry overflow point to a lower level If problems persist contact the Programme Office CHAPTER 10 ROLE OF KENDBIP Supervision and monitoring visits by the Programme The programme staff will always be checking biogas plants under different stages to ensure that quality is maintained The 3 following stages are checked 1 Under construction 2 Plant commissioning 3 After sale service Rc biogas programme staff will check plant under construct
14. e dust and loose particles to allow strong bonding of the mortar in between Tools Radius stick spade brick trowel bucket hoe wheel barrow measuring boxes Fixing of inlet pipe s The plastic pipe of 10 cm diameter is placed into the digester wall at a position which should be 300mm from the floor slab Position the inlet pipe of the mixing chamber directly in line opposite the slurry outlet manhole opening In case of a toilet connection of the toilet pipe can be installed lower than the inlet pipe from mixing chamber but it should not go above the lower slurry level to avoid gas escape through the toilet Toilet attachment to the plant need to be constructed with a pan without siphon or trap to avoid excessive water inside the digester affecting the hydraulic retention time and total solids in the slurry It is also not possible to de block the pipe if siphon is placed The inlet pipe from the toilet should not discharge farther than 30 from the hart line Additionally the pan level of toilet should at least be 60 cm above the overflow level in the outlet walls Note that this pipe connects the digester and the mixing dung chamber at the cow shed it is inclined at an angle direct to the centre of the digester and reinforced with concrete mortar on the outside For details see the technical drawing Building the dome Dome construction starts where the wall ends Note there is no dome ring beam Step 1 prepare a form work to support the
15. eeded Construction of toilet if needed Proper disposal of debris INDOOR PIPING Reduce the size from to 2 and pass it through a hole in the wall to the respective consumption point s Installation of appliances Biogas is denser than air therefore a biogas lamp is installed in downward position to facilitate gas combustion Biogas needs a lot of air to burn the burner must have air rationing mechanism to control the amount of air Biogas contains about 35 Carbon dioxide and therefore does not explode in a flame with air Fixation of gas taps rubber hosepipe stove and lamps Gas lamps are usually hung on walls or at the roof ceiling depending on the type of lamp A gas valve is also provided to control the gas flow as well as the brightness turning the device on and off The lamp should NOT be installed directly above the stove area due to risk of contamination Stoves at the kitchen are connected to the gas line by using flexible hose pipes and put on a table or down on the floor depending on the user Checking for leakages After installation each section of the piping system has to be pressure tested for gas leakages For this purpose a pressure indicator has to be used Basically it consists of a mouthpiece to blow pressure in the piping system and a transparent plastic U pipe which has two sides of more than 1 m length The pipe is filled with water and installed in the kitchen The set up is connected to the T joint at the test
16. gas utilization points in terms of distance and slope so that costs are reduced in piping material and water trap provisions Consider clients future plans like house expansion new house construction increasing number of animals etc Where these structures don t exist and a biogas plant is required it is necessary to consider them in the initial planning such structures ease the work for dung collection mixing with water and feeding Cowshed or Pigsties Depending on the cowshed or pigsty which should be connected to the plant the direction for slurry flow should be established in case of agricultural plant connected to toilets it doesn t only solve the problem of emptying the filled up pits but also brings about a better and safe use of human wastes for agricultural production It is important that the slurry out let is always at a lower point than the plant After these considerations laying out of the biogas plant can be done CHAPTER 4 CONSTRUCTION A Types and quality standards of construction materials CEMENT Cement should be good and high quality Portland cement from a brand with a good reputation should be stored 20 cm away from any walls SAND Sand should be clean and not contain soil or other material dirty sand will have a very early negative effect to the structure Coffee wire should be used to remove any unwanted materials Coarse and granular sand are suitable for concreting work however fine sand should be used for pla
17. ick to get the diameter Tools Radius stick peg plumb bob string Casting concrete of Foundation base Step1 Using a radius stick establish the slab ring Step 2 level the base and incase of a cone dig the depth according to drawing Step 3 establish the slab height by use of pegs leveled by a spirit level Step 4 Pouring concrete on the slab to a depth of 75mm together with the floor of the digester Step 5 Using the radius stick immediately lay one or more courses of bricks blocks Step 6 The first course of bricks is laid at half brick while the rest are laid quarter brick 9 The mortar ratio of 1 cement to lime to 4 sand 1 1 4 4 Or lay blocks in the normal way It is important to use the technical drawing from the beginning in order to have all the dimensions in place Tools Radius stick brick trowel spade hoe wheel barrow measuring boxes Construction of a wall 1 Allthe stones blocks bricks are dipped in water to clean and improve binding before they are used for construction 2 Lay the bricks in a quarter positions guided by the radius stick as a gauge for the 1st 3 courses then lay bricks normally for rest of the courses OR lay the blocks normally 3 Construction of slurry outlet manhole of 60 cm is done simultaneously Use spirit level or plumb bob to ensure vertical walls 4 Reserve space to position inlet pipes while constructing The stones blocks brick wall should be watered in order to remove all th
18. icks in spherical shape while constructing This gives the measurement from the radius point to the inner wall of the hemispherical digester The radius stick end can spin around the nail or round iron bar and can be fixed with binding wire or manila rope How to make a radius stick Several ways can be applied whereby the radius of the digester is marked by a nail at the length of this piece of timber alternatively steel or bamboo can be used The importance of the radius stick is to ensure that all blocks and bricks go round on a given radius and it makes a round and a dome shape Methods of digging the pit Pit digging depends on the digester size The radius of any digester is increased by 40 45cm to allow working area around the digester Where ground water table is high a small pit is dug aside the digester pit to allow water to collect so that it can be removed manually or pumped out when digging continues Soil scooped from the pit should be placed at least one meter away from the edge of the pit It is advisable that digging should not be done during rainy seasons and dig a cone incase of loose soil Tools Radius stick peg plumb bob spade mallet Fixation of the centre point For the construction of the wall and dome a GI pipe is fixed at the radius point and defined in the middle of the excavated pit below the reference line The distance to the reference line is given in the drawing From the center point use radius st
19. improve the livelihoods and quality of life of rural farmers in Kenya through exploiting the market and non market benefits of domestic biogas Biogas in general The gas and its composition Biogas is a combustible gas produced by anaerobic digestion of organic materials like animal dung agricultural wastes and human excreta During the anaerobic digestion process methane CHa 65 carbon dioxide CO2 35 and traces of hydrogen sulphide H2S are produced as by products The gas is only combustible if the quantity of methane in the mixture is above 50 After these organic materials have been digested they go out as slurry which is a rich fertilizer for agricultural production Some properties of Biogas Colorless It has a rotten egg smell due to a presence of hydrogen sulphide Flammable Ideal Conditions for gas production Biogas is produced by anaerobic absence of air digestion of organic materials Three different groups of micro organism act on the substrate under airless condition at different stages of digestion process and their collective name is putrefactive or methane bacteria Other conditions are Temperature 20 35 0C pH Neutral Retention time 40 60 days Dilution 1 1 dung water Benefits of Biogas 1 Biogas provides energy to cook reduce workload for women for collecting firewood and time saved can be used for other activities 2 Improving health by not using firewood and reducing indoor a
20. int nnne Eum m XEM d gt Gravel ballastz3 nette e ete aaa ta dee edes Dee e teet eee ad oett eee te edu aa ia e Bricks aic e ete ee dede e eH pee eee Ra anna cb desee e e rue PS PROCOSS is iei Oneida etu auam aiii g Methods of laying out of Biogas Plant cccccecscsscessessesssssesseessessecseceecsesescssesaaeeeesasseescaseessaesasenes Fis he Reference Linie ia e ite etie ae pa m ce edt i Steps for setting up the reference line esses esee nnnn nnne ennt nen j The Radius Stick and its importance in the dome construction esses eee neret k Methods of digging the pit ccscsscsssssscesssssesssssssscssesseessssssssssaessecesssesesseaseaseassesssassssscasssecesssasenseassasenes Lo Fixation Of the centre pOint ere mede e id e vad e D e e ds m casting concrete of Foundation base esee isses eese enetn etn th netta tetra tns tas ets saneta seas nasa aaa n Wall ConstEuctilon xii eee e deter en e opted E ene Fede ertet eie e eee 0 FIXING Of inlet pibe cremonese a er o d t gr qd Ae a p Building the dome cst ee Ed ORE d aer e Gi Plastering digester i tone eei e e mv a endi r Backfilling 3 ite RR ere ite trib im Eden c ON sS sCuring OF WOU to iancta ii tin RUD ninm diututitelutea ie hee t Fixation of dome gas pipe u sscssccesssecesssssessesessensssssessessessecassssesssasenseasessessssssscaessecassaesesseasenscaasessenssases u Plastering of the upper p
21. ion for the following issues Presence of Sales contract Quality of material used Center to Center distance digester expansion chamber Check radius stick wall amp dome Check radii wall dome height of wall dome amp exp chamber Reference line Lower slurry level bottom Inlet pipe s height amp direction Plaster ratios and thickness 2 cm Floor concrete quality Location layout of plant Kitchen stable slurry flow water Presence of shade over the biogas plant or presence of roots from trees Reference line stable floor inlet floor Programme staff will provide feedback to masons and users of their findings 22 APPENDIX A FORMS The following forms are relevant for masons within the domestic biogas programme contract between KENDBIP and mason contract between mason client and KENDBIP Plant completion report After sales service report 4m3 KENDBIP KENBIM LIST ITEM DESCRIPTION 4m3 6m3 8m3 10m3 12m3 A General bulk Materials UNIT QTY QTY QTY QTY QTY 1 Cement 50 kg bags 13 17 20 22 2T 2 Water proof cement 1kg bags 3 4 5 6 f 3 Quarry stones dressed Blocks 390x190x150mm pcs 145 180 220 270 290 4 Bricks 230x110x70mm pcs 180 260 300 340 400 5 Sand tonnes 3 4 9 6 7 6 Ballast 25mm 1 tonnes 2 2 3 4 4 7 Lime 25kg bags bags 45 6 7 8 8 Round b
22. ir pollution 3 Agricultural productivity by encouraging zero grazing 4 Environment protection and sanitation reducing water pollution Uses of Domestic Biogas e Cooking using special biogas stoves or modified conventional stoves e Lighting using special biogas lamps or modified kerosene pressure lamps e Refrigeration Baking ovens Chicken incubators and brooders replacing charcoal kerosene or electricity e Used for house warming and heating equipment Different models of biogas plants e Fixed dome Continuous Semi batch Batch e Floating drum Balloon Fig 1 Fixed dome Biogas Plants 1 1 Biogas plant from Chengdu China 2 Janata plant from India 3 Dheenbandhu plant of AFPRO from India 4 Modified BORDA from Burundi Different Components of a biogas Plant The cylindrical and hemispherical masonry structure that is constructed underground following specific vertical and horizontal dimensions as per respective technical drawing details It consists of Dung and urine mixing chamber connecting a shed and digester The digester for anaerobic digestion The slurry outlet and man hole Expansion or compensation chamber with over flow The slurry canal Slurry storage pit How the biogas plant operates The plant feeding is done through inlet pipe into the digester where an anaerobic digestion occurs this internally built gas pressure pushes digested slurry out through an outlet opening to the expansion chambe
23. lignment and digging of trench The piping system of a fixed dome digester can be several hundred metres long The pressure of the digester is enough to transport the gas required for normal cooking The piping system is a crucial part of biogas technology and to be established with maximum care All outside piping main gas line is done in 1 to 74 to 72 class C PVC plastic or galvanized steel pipe or PPR pipes The selection which type of pipe to be used is based on distance to the utilization points Type of soils salinity of soil will corrode steel pipe affordability convenience availability Step 1 Trench digging minimum 45 cm depth and 35 cm width for both PVC plastic pipes and galvanized pipe Step 2 Connect the main line with the testing unit Step 3 Determine the position of the water drain establishing a water drain valve at a T joint mounted at the lowest point along the pipeline Just before the drain valve an extension of about 25 cm 77 pipe pointing 45 degrees downward should be employed Step 4 Construct protection chamber for the water drain valve 50cmx50cm include a cover with lid Step 5 Fixation of piping to the wall of the house near the utilisation point Step 6 Backfilling the piping trench Draining should be carried out regularly i e once in a month Tools Grease Seal tape portable pipe vice hacksaw wheel cut measuring tape thread machine water drain valve wire brush pipe wrench
24. naa a Composition of biogas slurry ecsssessessesseessessesssssesssssessscessesssssasessesssasesssessssssnscassaecesssasenseasecseaasesseess b Uses of biogas slurry csssssesscssesseesesssesssesssssessssecessassessesssasesssesessssssssssssessecasssesesssaceaseaseesssssssscassascaseaes c Slurry distribution and application methods scssssssssessessecescessessessesseesesssesssssssssesssaecesssasessesssscsnssaseeessases viii Chapter 9 trouble shooting c cccececsessssssssssessessesesecseceeseecsesessessessesesssesesessessesasseesessessessesseaseaesessessesaes ix Chapter 10 role of KENDBIP c ccccccsecsecsessssssssssescessecsessecaecaesessessessessessesssesuesuesascaecaeseseesesaesaesaeaseess X Appendix Pane a Forms b Roles of mason c Roles of supervisor d Promotion and marketing e User manual NOMENCLATURE KENDBIP Kenya National Domestic Biogas Programme BMT Biogas Mason Training CHAPTER 1 INTRODUCTION Need to train masons Building of a quality bio digester requires good knowledge and skills on the part of the constructor the mason Good functioning or performance of a bio digester is associated with the selection of the right size choosing the right site for construction selecting the construction materials and appliances to comply with the quality standards constructing the components with strict adherence to the norms and ensuring effective operation and maintenance activities most of whi
25. nt gas pressure Pressure indicator Manometer Nos 8 9 10 11 shows how the line should be tested for leakage No 12 13 and 14 shows gas flow and consumption rate co 7 00 REGN Some new technologies and modification of gas appliances Special biogas lamps and stoves are provided at a cost by the programme Conventional LPG using appliances like lamps stoves and refrigerators can be modified to use biogas Different engines using diesel or petrol can be modified to utilize biogas All modifications should be done by skilled technicians Gas Utilization Decisive parts of a gas burner are the e Jet or nozzle e Primary air intake e Secondary air access of the flame to e Exhaust gas which has to disappear from the flame without hindering the secondary air to reach the flame The flame can be adjusted comfortably to be stable and not too wind sensitive under the bottom of the pot The highest adjustment of the stove knob should not lead to a flame which leaks around the pot and burns the plastic handles The performance of the flame depends among others on the quality of the gas the altitude of the location and the gas pressure in the digester For the performance tests the flame burns better if a pot filled with water is sitting on the pot rest or a bit above The sketch shows the different parameters on the flame The example shows the ideal case small blue flames completely under the pot best energy efficiency 9909Q0QQQQQQQ
26. ogas in the district Train end users on proper usage and taking care of biogas plant PROMOTION AND MARKETING The programme will work with local authority and NGOs to promote domestic biogas in the entire district that the masons are working in E Develop and distribute promotion material Train and assist local promoters and provide incentive for identification of clients Supervisors might assist masons in visiting clients Programme provide subsidy to make domestic biogas more affordable USER MANUAL HANDED DURING COMPLETION REPORT SIGNING Purpose to link the programme to the user Information on topics such as cowshed The plant what could be possible problems with possible remedies recommended to the user piping problems Appliances Slurry use Masons Supervisors One page poster with main uses Bio slurry use and management After sales service warranty period and details of what the user should expect out of that period Common mistakes 25
27. r Steps for setting up the reference line Step 1 After setting the demarcation of the plant fix a post 1 at the lowest point of the stable Step 2 Position peg number two at point of slurry overflow at a height of 10cm above ground and fix a post 2 1m away in line with peg 1 and 2 Step 3 Measure 100cm above the top level of peg number 2 and transfer the measurement to post 2 tie a string at that point Step 4 Use water spirit level to get a point at post number 1 Step 5 Fix a string between post number 1 and 2 in horizontal position passing over the center of the digester Step 6 Verify if lowest point at inlet with reference line is 15cm or less 8 Step 7 If more than 15cm reposition peg number 2 Step 8 Indicate both center point for digester and expansion chamber on the reference line by fixing small nail on those points In order not to lose the level of the reference line it is advisable to also mark it on a tree or building near to the plant In case of slope setting of reference line should be along a contour or across the slope The same 10cm is applied in slope situation Displacing the reference line will influence negatively the amount of gas to be stored the pressure and the slurry movement Tools pegs string nail spirit level water level The Radius Stick and its importance in the dome construction This is a guide stick measured specifically for controlling the radius of the digester and controls the br
28. r and finally out through an over flow point and slurry canal CHAPTER 2 SIZE SELECTION Guideline for the selection of the proper size of the biogas plant Sizing follows three parameters daily feed retention time and digester volume Consumption based on 60 days hydraulic retention time amp ambient temperatures 20 25 Given 1 cow produce an average of 15 kg of dung per day Mixing ratio of dung to water urine 1 1 1 kg of cow dung produce 40 litres of gas per day 2 cowsx15kg day 30kg day Dilute at ratio 1 1 30kg dayx2 60litres Retention time of 60 days 60litresx60 days 3600 litres Volume 3600 1000 3 6m 4ms No of normal Daily dung Water Number of Number of Digester adult animals Feeding Urine To H H Stoves amp Lamps amp size Cows Kg mix with running time running time at m3 Dung Lts ata rate a rate 200 120 180Its 350lts hr hr 4 1 2 30 30 1 Fo3 1 For2 hours hours 6 3 4 44 44 1 Fo4 1 W fFor45 hours hours 9 5 6 70 70 1 For6 2 For3 5 hours hours 13 7 8 104 104 1 For6 3 For6 hours hours Observations f cows are out door grazed multiply with 3 the number of cows Pigs manure can equally be used and provides even more gas than cow dung Kenyan household uses around 6 hours for cooking Looking for client personal information Clients energy requirement Clients priority plans and future prospects
29. ressure inside the plant The slurry out let manhole between the digester and the expansion chamber allows slurry to flow in and out following the gas use and gas production respectively The foundation for the expansion chamber is made out of concrete at the ratio of 1 3 4 or 1 2 4 depending on the size of aggregates Set out the foundation according to the drawing and set the 4 corners of the walls checking the diagonals for square ness Build the walls up to required height leaving overflow opening at the correct height from the reference line Apply plaster accordingly at a ratio of 1 5 after at least 1 day waiting Construction of Mixing Chamber The mixing chamber is constructed to mix dung and water and make the required paste e The foundation of the inlet pit should be placed in well rammed hard and levelled surface e n this rammed surface first of all the rectangular base of mixing chamber is constructed The height of the base should be decided in such a manner that the floor of the mixing chamber is at least 10 cm above the outlet overflow level e The circular mixing chamber measurements are 600mm diameter x 600mm high e The proposed minimum urine collection chambers measurements are 55cmx80cmx20cm e After brick laying is done after at least 1 day waiting both inside and outside of the chambers are plastered with cement mortar 1 part of cement to 4 parts of sand CHAPTER 5 PIPING Fixation of pipeline a
30. ry in the pipeline Problem Possible causes Remedies Insufficient gas pressure max Gas leakage along the pipe Check for any gas leakage and solve the plant pressure not reached line problem Under feeding of the plant Ensure the feeding instruction is followed 20 and daily feeding is carried out Gas not enough as it used to be before Underfeeding of the plant Possible leakages through gas tight zone Possible gas leakages along the pipe line Scum formation inside the digester Dung water mixture not at the right proportion to the one incorporated in the digester design Siltation accumulation of inorganic solids inside the digester Ensure the feeding instruction is followed and daily feeding is done for a constant gas production Check for gas leakages and gas tightness inside the plant when necessary emptying of the plant should be performed in order to inspect and solve the problem Bio effluent smelling at the expansion chamber amp canal Over feeding of the digester Feeding instruction to ensure a good consistency of the mixture should be followed Gas stove not burning well Blocked primary air ducts Blocked flame holes Incorrect gas air mixing ratio Presence of water in the pipe line Poor stove design Clean all the air ducts and burner holes regularly to prevent blockages Adjust the primary air knob in order to get the right mixture
31. s Plan lay out and digging of pits Construction of biogas plant and chambers Laying of pipelines and installation of appliances Advice on the use of bio slurry as fertilizer Carry out guide households on how to operate and maintain the plants Provide after sales services Masons should be familiar with their roles and responsibilities related to Promotion Quality Management and extension of biogas slurry uses Biogas Technology History and its development in Kenya The first biogas digester was built in Kenya in 1957 to provide gas and fertilizer The effluent was found as an excellent fertilizer The German development cooperation GTZ started promoting biogas in the middle to late 1980s in Kenya in collaboration with the Ministry of Energy under the Special Energy Programme It opted for the floating drum type possibly due to local steel manufacturing capacity and built approximately 400 biogas units a high proportion of digesters appear to operate below capacity are dormant or in disuse after construction because of management technical socio cultural and economic problems Consequently biogas technology acquired a less favourable reputation and the penetration rate in the country remains very low It is impossible to estimate what percent remain in working condition due to the dispersed and sometimes uncontrolled and informal nature of installations Biogas Programme objectives The proposed goal of the programme is to
32. s production CHAPTER 8 SLURRY UTILIZATION Definition This is a product obtained after manure is digested in a biogas plant Slurry usually flows out of the expansion chamber in large quantities at night due to the accumulation of pressure caused by unused gas overnight Gas pressure tend to displace the slurry in the digester dome by pushing it out through the expansion chamber Composition of biogas slurry Biogas slurry is composed mainly of the following 1 Solid plant materials 2 Water 3 Nutrients i e ammonia NH4 nitrogen and phosphorous Uses of biogas slurry Slurry is used as 1 Manure for crops improves soil fertility improves crop production 2 n fish ponds to enhance the growth of algae It has been found to be better compared to the raw manure 3 Used as a partial supplement in the rations of pigs and fish meal Importance of biogas slurry 1 It contains essential nutrients like Nitrogen and phosphorous that is good for plants 2 Reduces the cost of buying chemical fertilizers Slurry distribution and application methods 1 Open trenches slurry will flow to the farms through gravity 2 Manually using wheelbarrows and buckets in this method wheelbarrows containers must have lids since the slurry is in liquid form 3 Mechanically tankers fitted to lorries or pulled with tractors are used amp Pumping systems use of pipes CHAPTER 9 TROUBLE SHOOTING Potential problems and likely solutions ex Slur
33. screw driver and oil can Bio gas sites differ from one another due to different terrain and nature of topography to the gas consumption point i e variable slopes 12 Such earmarked features include 1 Flat terrain level grounds 2 Slope towards the consumption point 3 Slope towards the bio gas plant and 4 In case of long gas pipe line depending on the topography of the respective site the ground tends to be undulating thus going up and down The following drawings illustrate the right position for the water drain installation preferably the drain valve should be mounted either just after the plant or before the consumption point 1 Slope towards the bio gas plant Figure 1 Piping system with straight slope from kitchen to digester No water trap required as condensation water drains into the digester 2 Undulating terrain WATER TRAPS 14 Figure 2 Wherever condensation water cannot drain back into the digester a water trap becomes necessary Figure 3 Automatic water trap 1 T joint in the piping system 2 water column equal to max gas pressure 30 security 3 solid brick or concrete casing 4 concrete lid 5 drainage Figure 4 Manual water trap 1 T joint 2 buffer storage for condensated water 3 manual tap 4 casing 5 concrete lid 6 drainage The asymmetrical U trap is the best option in terms of cost and operation The advantages include Diagram
34. stering works River lake sand is well graded hence preferred Avoid dusty sand GRAVEL BALLAST The size of gravel should neither be very big nor very small and should be clean hard and angular in shape If dirty should be cleaned first before use and the maximum size of gravel should be or the slab thickness BRICKS Bricks should be of high quality made in the size of 23cm by 11cm by 7cm and the brick should be well burnt straight and regular in shape and size In some area that you cannot burn you may use bricks made of cement of the same size at the ratio of 1 8 Quantity requirements of construction materials BOQs refer to the appendix B Process Methods of laying out of Biogas Plant 1 Locating of suitable position for the biogas chamber 2 Fixing the relative positions of mixing chamber inlet digester manhole expansion chamber and slurry pits 3 Using the respective drawing and their horizontal dimensions and add 45cm to the digester and expansion chamber radii to allow working area for the wall and plaster 4 Using Colour powder to indicate demarcation The Reference Line A reference line is a thin string connecting two leveled points passing across the centre of a biogas plant from which all vertical measurements are taken Main vertical measurements of the working drawings are given in relation to the reference line The reference line is 100 cm above the overflow point 10cm above ground of the expansion chambe
35. unit chamber which is along the pipe line All ends of the piping system are closed and air is blown into the mouthpiece until the water in the transparent hosepipe develops to a level difference of 1m If this level difference remains constant the pipe line is gas tight When the pressure drops there must be a leakage somewhere which has to be detected and fixed before the work on the piping system continues To detect a leakage brush and soap water are used in case of a leakage soap bubble will be formed Leakages occur mainly at joints unions and particularly where hosepipes are connected to the fixed piping system Such weak points need to be minimized and tightened Function of Test Unit Chamber The test unit chamber is used for the quality management by the domestic biogas programme Apart from pressure measurements leakage detection in the piping the test chamber is used for determining the amount of gas in use through an installed gas meter The gas meter measures the amount of gas which goes through it when going to the use points The gas meter measures in m3 hr The gas meter is connected to the two T fittings at the test chamber by passing the gas valve so as to allow gas flow when in use oP T oo the i E b A Me 5 A e Drawing No 8 An area for monitoring the plant performance amp gas leakage Test unit chamber with lid Main gas valve A T fitting connected A second T joint Measuring of the pla
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