Local Oven for Charcoal Production in Kenya


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Local Oven for Charcoal Production in Kenya

  1. 1. Local oven for charcoal production An appropriate alternative for carbonizing materials into charcoals Takuro Haraguchi Kopernik Fellow -Tokyo Institute of Technology Department of International Development Engineering
  2. 2. Contents1. Introduction 3p2. Collection 4p 2.1 Bricks 4p 2.2 Mud 4p3. Building the oven 6p 3.1 Theory 6p 3.2 Let’s build up 7p 3.3 Covering outside of the oven 12p4. How to use it 16p 4.1 Putting materials inside. 16p 4.2 Lighting the fire 16p 4.3 Cooling down 16p 4.4 Taking out charcoal 17p5. Supplem ent 18p 5.1 Making a better structure 18p 5.2 Lowering the cost to build an oven 18p 2
  3. 3. 1. IntroductionWhile managing the charcoal project in Kenya, which uses technologydeveloped by MIT D-lab that allow the production of charcoal fromagricultural, I faced several problems.One of the biggest hurdles for beneficiaries who were willing to get involvedwith the project was the initial cost of getting a drum, a necessary equipmentfor carbonization of agricultural waste under D-lab’s technology. That isbecause many of the participants live in impoverished villages and are not ina position to meet even some basic needs, and thus cannot afford to get adrum which cost 1,700Ksh (16.63 USD 1). Furthermore, they have to gotowns to obtain it, making it even more inaccessible. Initially, I tried tomanage the situation by using a loan model. This model consists of providinga loan and getting it repaid after 6 months from the profits of producing andselling charcoal. After 6 months however, when I came back to Kenya, Irealized that they could not generate enough income from the charcoal projectbecause several problems resulted in an underproduction of charcoal. At thesame time, I received many requests from people in village to becomebeneficiaries of this project, although ultimately they were unable toparticipate because of the cost of the drums. Therefore, from the initialprocess of this project, it is evident that we must provide alternative ways toget involved with this project. It is important to consider accessibility for thepoor when introducing a technology.A key word and possible solution to tackle this issue is “Localization”. Thereare many local technologies that are still unknown. There is a possibility tocombine ideas from local technologies and our idea to solve the problem. Oneexample is using an oven with bricks to substitute for the drums, which I willexplain in the next section. Many villages in western Kenya uses bricks thatare made from soil by local people, which means that bricks are accessibleand cheaper.1 I converted Kenyan currency to USD by this ratio USD/KES = 0.00978, 13th Oct 2011 3
  4. 4. 2. CollectionBefore creating an oven, you have to prepare two materials: bricks and binder,which are available at villages, eliminating the necessity to go to towns tocollect materials.2.1 BricksBrick is a fundamental material to develop this structure. Of course, you canmodify it to the oven design you want to make. But, I would like to show abasic model of this structure here.First you have to access a place where you get baked bricks. You will useabout 100 bricks. So, cost of getting bricks is about 500Ksh(4.86 USD)because the cost per brick is just 5 Ksh.2.2 MudIt is very important to think about binder connecting bricks and making theminto a very strong structure. So, what we can use locally is soil. Actually,people in villages already know how to make good mud from soil. People in villages use mud for building their houses. 4
  5. 5. 2.2.1 Making mud The first step is to dig up soil by spade and add water. After that, you mix it with water by using spade and stepping on it by foot until mud reaches a consistency that is well mixed and sticky.2.2.2 Fermentation After making mud, we devise it to be stickier by fermentation. First, you collect mud in one place like the photo to the left.Second, you cover it by plastic paper for more than 3 days.After 3 days, the mud is stickier. And you can know that the mud was indeedfermented from simply detecting the smell emanating from the mud. 5
  6. 6. 3. Building the ovenAfter collecting the above two materials, now you can develop a local oven.3.1 TheoryBefore actual construction, I would like to explain 4 structural requirementsthat enable us to get good charcoal.-1: A hole from which we put agricultural waste in it.Before starting to carbonize, agricultural waste must be inside a structureand so you need a hole from which you will place the materials inside..-2: Holes from which the waste will catch fire.After putting the materials inside, you need to ignite them from bottom holes.-3: No hole from which heat can escape.After burning, you cover all holes so that you can stop providing oxygen whilemaintaining high temperature and pressure.-4: Places from which to take charcoal out.After cooling down, you can get charcoal from those places.With these requirements in mind, we designed the following oven. 6
  7. 7. 3.2 Let’s build upWe can divide this structure into three parts: bottom structure, middlestructure and top structure. And, you need to add mud between bricksfrom now to connect each other without removable bricks that Iam going to talk about at 3 rd layer.3.2.1 The first and second layer (Bottom structure)To meet the requirement number two, we devise the first and second layer toaccommodate holes from which we can supply burning material to fuel thefire.- First layerThere are spaces between bricks (see Figure 1 and Figure 1a below) whichare equal to the size of the bricks so we can insert bricks to cover this spaceand prevent heat from running away during the cool down process. . Figure 1 Figure 1a- Second layer From this point on, I would like to explain step by step. First, you put 6 bricks on top of the first layer as shown in red to the left on figure 2.Figure 2 7
  8. 8. Figure 2a Figure 2b For step #2, you put another 8 bricks on the top and bottom, which are drawn again in red thick lines on Figure 2a. Figure 2b shows the actual layout. The last step for the second layer is to fill 6 spaces by splitting bricks so that they fit into the small spaces around the perimeter. These small spaces are shown by the 6 rectangles drawn in red thick lines on Figure 2c.Figure 2c Figure 2d shows the complete second layer.Figure 2d 8
  9. 9. 3.2.2 The third, fourth, fifth and six layer (Middle structure)After completing the second layer, it is now time to build up the structurearound the edge. For step #1 of the third layer, you will need to pile up 12bricks on top of the edge of the second layer (see the green rectangles onFigure 3 below).- Third layerFigure 3 For step #2, you fill 4 spaces by splitting bricks as you did with the second layer to fit into the gaps. The 4 squares that are painted in darker green on Figure 3a mark these 4 gaps that need to be filled.Figure 3a 9
  10. 10. Please look at Figure 3b to the left. The two darker green squares indicate the 2 bricks that will become removable bricks. You must not attach mud on the edges of these removable bricks.Figure 3b- Fourth layerFor the fourth layer, you pile up bricks in the same exact way as the thirdlayer. Please be careful that there are 4 removable bricks in total onthird layer and fourth layer and not to attach mud on theseremovable bricks.- Fifth layer.On the fifth layer, pay extra attention to the removable bricks on the thirdand fourth layer. You will have to pile up bricks on top of them, but thestructure must be stable even when you take out the removable bricks. Thekey to creating this stability is the two bricks right above the removablebricks—they must be supporting each other. You can achieve this byconnecting the sides of these two bricks and make them lock. Refer to theinstructions and diagrams below.Figure 5 Figure 5a (aerial view) 10
  11. 11. Figure 5bFigure 5 shows the side of the oven where the removable bricks are clearlyvisible. To achieve this, you must make a secure connection of the 2 brickson the 5th layer right above the removable bricks (shown in orange onFigure 5a). Figure 5b shows a side view of the oven thus far. Note the circledrawn on the 5th layer on Figure 5b; that’s where the 2 bricks above theremovable bricks (shown in blue) need to be connected.- Sixth layerFor the sixth layer, pile the bricks as you did in the fifth layer.3.2.3 Seventh, eighth and ninth layer (Top layer)For the seventh to ninth layers, you begin to make the hole on top. Theperimeter of the bricks must gradually taper with each layer as illustrated inthe diagrams below.- Seventh layer - Eighth layerFigure 7 Figure 8 11
  12. 12. - Ninth layerFigure 93.3 Covering outside of the oven3.3.1 First cover (Before being dried) After building up, you have to cover holes on the surface by mud. The trick of attaching mud is to pelt it on the surface instead of applying.Figure 10 12
  13. 13. 3.3.2 Second cover (after being dried) The purpose of second cover is to cover small holes that still exist after drying the first time, mostly because some mud falls down in the process of drying due to wind or rain (see figure 11). So, after first round of drying, find small holes on the surface that will allow matter to seep inside and cover them by pelting mud again. Figure 113.3.3 Third cover (after being dried again)The purpose of the third cover is to cover cracks. You will notice thatthere are many cracks on the surface after the mud becomes dry (seefigure 12 below). So what you should do is to cover again, but thistime use another type of mud that does prevent cracks fromoccurring: a mixture of mud and cow dung are normally used forbuilding up foundation and wall of house in villages, and will suitthis purpose as well. You can see how that mixture works after itdries on figure 12a.Figure 12 13
  14. 14. Can you see the difference? There are no cracks on the surface of this wall. By using this mixture, we eliminated cracks because the mixture of mud and cow dung is so sticky that cracks do not appear even after being dried.Figure 12a3.3.4 Preparing mixture of mud and cow dungYou put soil on cow dung and add water.Figure 13 Figure 13aThen mix it together.Figure 14 Figure 14aAnd unlike with mud, apply and do not pelt this mixture on the structure. 14
  15. 15. Figure 15 Figure 15aAnd your oven is now finished! If you don’t cover the oven with this mixtureas a final step, it will fail to make good charcoal because heat will escapethrough cracks and holes, as seen on figure 16 below.Figure 16 15
  16. 16. 4. How to use the oven4.1 Putting materials insideThis process is the same as using a drum. You put it in until it is full. Onedifference here is the size of the container. This oven is 1.5 times bigger thana regular sized drum so that more materials are needed to fill the oven.4.2 Lighting the fire Similar to when using a drum, you have to insert materials to burn (fuel) from the four holes that are located at the bottom.Figure 174.3 Cooling downOnce the fire is large enough to reach top of this structure, cover the hole onthe top and 4 holes on the bottom to prevent oxygen from getting inside andheat from escaping.- Covering the hole on the topDo it the same way as you would with a drum by placing an ion sheet andputting soil on it.- Covering 4 holes on the bottomA significant difference of the stove compared to a drum is that it attacheson the ground. If we use a drum, we remove stones on the bottom and putthem on the ground before sealing the bottom edges and the top of the drumwith sand. With the stove, however, you place four bricks into these holesinstead to cover up the oven, and then you seal it tight with sand. Theresult will look similar to Figure 18 below. 16
  17. 17. Figure 184.4 Taking out charcoalAfter you confirm that the bricks are not hot, then it is safe to take outcharcoal from inside. First, you take out the removable bricks from both sides,as shown below.Figure 19 17
  18. 18. Then remove the charcoal inside with your hands.Figure 20 18
  19. 19. 5. Supplements5.1 Making a better structureA drawback stated by beneficiaries about this oven is that the holes on thefirst (floor) layer are so big that carbonized materials fall down very easily. So,they came up with a solution to prevent materials from falling down byputting iron mesh, regularly used for grilling meats, on those holes to capturethe fallen, carbonized materials.5.2 Lowering the cost to build an ovenOne way to bring the price of this oven down is to use unbaked bricks, whichare 2 Ksh per brick, lowering the total cost to 200Ksh. You may think thatunbaked bricks will not support the structure as strongly as baked ones;however, the process of carbonizing materials with fire will essentially bakethe bricks because the process is the same for baking bricks from mud. Thus,the more you use the oven, the more firm and stronger the oven will become,making the 200ksh alternative oven a more viable possibility. If you have any questions or suggestion, please let me know. takuro.haraguchi@gmail.com Takuro Haraguchi Kopernik Fellow Tokyo Institute of Technology Department of International Development Engineering 19