Institutional Rocket Stove Manual 653g41

Editor: Rosette K. Kabuleta (GTZ – PREEEP) Text, Technical Diagrams and Photography by: Leonard Mugerwa Job Mutyaba Ritah Mubbala Cover page design by: Haruna Lubwama Advisory: Philippe Simonis (GTZ - PREEEP) John Kuteesakwe (GTZ - PREEEP) Godfrey Ndawula (MEMD) Published by: Ministry of Energy and Mineral Development (MEMD) Promotion of Renewable Energy and Energy Efficiency Programme (PREEEP) ed by the German Technical Cooperation (GTZ)

Date: First Edition: November 2004 Second Edition: November 2008 © 2008 MEMD – PREEEP

Table of Contents ACKNOWLEDGEMENT ...................................................................................... IV INTRODUCTION ............................................................................................ V THE TECHNICAL MODIFICATIONS IN THE ROCKET STOVE DESIGN .......................................... VI BASIC FACTS ABOUT THE INSTITUTIONAL ROCKET STOVES .................................... VIII 1.0 ECONOMIC ASPECTS (PAYBACK) ................................................................. X THE FIXED INSTITUTIONAL ROCKET STOVE........................................................... 1 2.0 THINGS TO CONSIDER BEFORE BUILDING THE INSTITUTIONAL ROCKET STOVE ............ 2 2.1 STOVE CONSTRUCTION MATERIALS ................................................................... 3 2.2 BRICKWORK .......................................................................................... 4 2.3 METALWORK .......................................................................................... 4 2.2 MATERIAL PURCHASE ................................................................................. 4 3.0 STOVE PLANNING .................................................................................... 5 3.1 MAPPING OUT THE STOVE POSITION ................................................................... 5 3.2 DETERMINING THE STOVE BASE DIMENSIONS ........................................................... 5 3.3 OBTAINING THE LENGTH OF THE COMBUSTION CHAMBER (L) .......................................... 8 4.1 PREPARING THE MORTAR; ............................................................................ 9 5.0 BUILDING THE STOVE ..............................................................................10 6.0 FINISHING THE STOVE .............................................................................15 THE MOBILE INSTITUTIONAL ROCKET STOVE........................................................16 1.0 THINGS TO CONSIDER BEFORE BUILDING THE MOBILE INSTITUTIONAL ROCKET STOVE .16 1.1 SHELTER .............................................................................................16 1.2 TOOLS ...............................................................................................16 1.3 SAFETY GEAR ........................................................................................17 2.0 STOVE PLANNING ....................................................................................17 2.1

BONDING AND INSULATING ........................................................................17

2.2

MOBILE ROCKET INSTITUTIONAL STOVE FABRICATION ..............................................17

2.3 PURCHASE AND DELIVERY ............................................................................18 2.4 STOVE ASSEMBLY ...................................................................................18 2.5 STOVE SIZING........................................................................................19 3.0 MAIN PARTS OF THE MOBILE STOVES ............................................................20 3.1 THE SAUCEPAN SKIRT ................................................................................20

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3.2 COMBUSTION CHAMBER BLOCK (WITH AN AIR BY)................................................20 3.3 BASE PLATE..........................................................................................21 3.4 THE STOVE/SAUCEPAN STAND ASSEMBLY .............................................................21 3.5 TOP RING ...........................................................................................22 3.6 STOVE TECHNICAL DRAWING ........................................................................23 4.0 FABRICATING THE STOVE .........................................................................25 4.1 THE OUTER SKIRTING ................................................................................25 4.2 THE INNER CYLINDER ................................................................................27 4.3 THE COMBUSTION CHAMBER BLOCK ..................................................................27 4.4 BASE PLATE .........................................................................................27 4.5 STOVE ASSEMBLY ....................................................................................28 4.6 STOVE INSULATION ..................................................................................30 APPENDIX: RELATIONSHIP BETWEEN SAUCEPAN / POT DIAMETER AND COMBUSTION CHAMBER ...............................................................................................34

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Acknowledgement This publication is attributed to the work done by several players. ‰

The initial work on the firewood saving rocket stoves in Uganda was done through the then Energy Advisory Project (EAP) in the Ministry of Energy and Mineral Development (MEMD), ed by the German Technical Cooperation (GTZ).

‰

The rocket – elbow combustion chamber was invented by Dr. Larry Winiarsky at Aprovecho Research Centre, Oregon, USA. Peter Scott of Aprovecho cooperated with GTZ – EAP to introduce it in Uganda in 2003.

‰

The prototype rocket stoves were developed and tested at the premises of the Uganda Industrial Research Institute in 2003 – 2005 and at the Faculty of Technology Makerere University Kampala in 2007. The from Dr. Izael Pereira da Silva of the Centre for Research in Energy and Energy Conservation (CREEC) is acknowledged.

‰

This revised edition of the household stove manual has been published with the of the GTZ - Promotion of Renewable Energy and Energy Efficiency Programme (PREEEP), for use as a training tool for stove artisans.

iv

Introduction Uganda faces a biomass energy crisis marked by an increasing imbalance between the supply and the demand for the firewood by households, institutions and industries. One of the most effective strategies to sustainably contribute towards the reduction of this problem is through an extensive dissemination of biomass energy efficient technologies. The biomass energy efficient technologies have been developed to improve energy efficiency for household, institutional and industrial practices. They include the domestic and institutional firewood stoves and the firewood baking oven. The institutional rocket stoves have overall efficiencies of over 40% (average) compared to the traditional (open) 3-stone fire stove at 15.6 %, in a laboratory high power water-boiling test1. These improved stoves help the s to have firewood savings of 50 – 60 % when compared to the traditional (open) 3-stone stove2. This implies that the amount of firewood used by a family in one day with a traditional 3-stone fire can be used for 2 – 3 days with the rocket stove. Yet another advantage of using the institutional rocket stove is the fact that investment on stove construction can be recovered in a relatively short time through money save as a result of firewood savings. The main objective of developing the improved firewood stoves is to achieve relatively efficient firewood combustion and maximising heat transfer to the food being cooked. The purpose of this manual is to provide to stove artisans a practical tool to use in construction of institutional rocket stoves.

1

MEMD – EAP stove rest report: Ref: http://www.crest.org/discussiongroups/resources/stoves/Scott/Uganda%20report.htm 2 MEMD – EAP: Institutional rocket stove end-s impact survey, April 2007 v

The Technical Modifications in the Rocket Stove Design Following the impressive performance of the prototype rocket stoves in comparison with the traditional 3-stone fire stove, the Ministry of Energy and Mineral Development (MEMD) through the then Energy Advisory Project (EAP), ed the private producers to disseminate several hundreds of the institutional rocket stoves. A monitoring and evaluation exercise that was conducted revealed that the institutions that adopted these stoves were able to: ƒ Increase efficiency in firewood use and to reduce environmental degradation through the adoption and optimum utilisation of the institutional rocket stoves. ƒ Improve the working conditions of the kitchen staff that are exposed to the hazardous smoke and intense heat emission from the traditional 3-stone stoves. ƒ Prepare and serve meals in time. However it was also noted that several institutional rocket stoves did not have firewood shelves because they had been worn out by fire. The other challenge was that the most of the institutional stove owners buy and use wet firewood because the dry firewood is rare on the market. In a GTZ regional workshop on household energy3 held at Mulanje Malawi in March 2007, some of these technical aspects were highlighted. It was agreed that there was need to have a design review in order to enhance stove performance, durability and satisfaction. EAP introduced several modifications in the institutional rocket stove design in order to improve the stove’s efficiency and durability and to enhance satisfaction. The major modifications include: ƒ Introducing a by air inlet in the design as a replacement for the firewood shelf which is easily destroyed by the fire, ƒ Incorporating a charcoal grate in the combustion chamber to trap the large hot coals to enhance their combustion prior to becoming ash, ƒ Fitting the saucepan design with a flange at the top to seal off the exhaust gases emission in the kitchen and to minimise the indoor air pollution by directing the smoke through the chimney. The flange also enhances the saucepan at the stove ring thereby reducing the wear of the saucepan s below. ƒ Coating the stove top with a waterproof surface e.g. terrazzo to protect it from the effects of food spillage ƒ Removal of the butterfly valve from the chimney because it is no longer necessary. It was concluded that for optimum performance, the institutional rocket stoves should henceforth be disseminated with the features described above. It is recommended that such stoves are constructed by qualified technicians who have considerable experience in the technical specialities of masonry / building construction, metal fabrication and industrial ceramics. This revised institutional rocket stove manual (November 2008 edition) describes the step-by-step construction procedure of the modified institutional rocket stoves with the by air inlet.

3

GTZ Report : GTZ Workshop on Household Energy, Mulanje, Malawi, 8 – 13th March 2007 vi

Disclaimer Whereas relative to the traditional 3-stone (open) fire place the firewood institutional rocket stoves are believed to offer significant benefits to the (s) including firewood savings, reduced time for cooking and reduced indoor air pollution and whereas this stove construction manual is believed to be a useful tool for instruction in the procedure for the construction of firewood institutional rocket stoves, neither the Uganda Ministry of Energy and Mineral Development nor the German Technical Cooperation assumes responsibility for the completeness or usefulness of the information herein. Additionally neither the Uganda Ministry of Energy and Mineral Development nor the German Technical Cooperation assumes liability in respect of any claim(s) that may arise in the event of any injuries and / or damages that may occur during the design, construction, use, maintenance or misuse of any stoves that may be constructed on the basis of the design or procedure described herein.

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BASIC FACTS ABOUT THE INSTITUTIONAL ROCKET STOVES The institutional rocket stoves are able to achieve maximum transfer of heat to the food because they heat at least 90% of the saucepan surface area and have insulation around the combustion chamber and fire ages. The institutional rocket stoves are made in two versions: 1. the fixed rocket stoves 2. the mobile rocket stoves Fixed rocket stoves are built in permanent shelters using bricks and mortar for the body work. They are more expensive but also more durable. When they are handled well, these stoves can last more than 10 years with only minor repairs required. They are made for a wider range of saucepan capacities than the mobile versions. The mobile version of the rocket stoves are easy to fabricate. They are made primarily of steel. These stoves are lighter and are meant to be used where there is no permanent shelter. They are recommended for use with saucepans up to 150 litres. They are also cheaper to fabricate. The choice of stove to be built is therefore determined by a combination of factors including: 1. capacity of saucepan desired/ number of people to be served 2. shelter needs 3. financial limitations 4. lifetime expectancy Advantages of using the Institutional Rocket Stoves 1. Saves money: These stoves have been tested and proven to be economical in firewood consumption. For example, an institution that spends UGX 600,000 on firewood per term using a traditional stove will only use firewood of less than 200,000 Shillings per term if they properly use a rocket stove. By using less firewood these stoves reduce firewood expenses.

viii

2. Cooks Faster: When compared to a 3-stone open fire, the institutional rocket stoves cook a given quantity of food in half the time. Where kitchen staff has been spending 4 hours to cook beans, it will only take 2 hours while using the institutional rocket stoves. 3. Less smoke: The rocket stoves hardly produce smoke. A bit of smoke is produced only when lighting the fire. (Note: The stove will also produce some smoke if wet firewood is used). Kitchen staffs enjoy a smoke-free kitchen. No more tears)!

4. Easy to Use: A does not have to blow air into the stove to fan the flame. Once lit, the stove fire will burn continuously unless one stops putting firewood into the stove. 5. Safe to Use: These stoves are safe to use because the fire is shielded. The kitchen staffs are therefore protected from fires and burns. 6. Environmentally Friendly: These stoves use less firewood leading to reduction of the deforestation rate.

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1.0 ECONOMIC ASPECTS (PAYBACK) The table below is a comparison of the costs involved between the traditional and institutional rocket stoves4. Parameter Investment (2 pot stove)

Institutional rocket stove 4,600,000 /=

Traditional stove

9 trucks a year

27 trucks a year

400,000 /=

400,000 /=

3,600,000 /=

10,800,000 /=

5 years

----

Firewood consumption per year Average cost per unit truck Annual running costs Minimum expected life time

•

1,200,000 /=

Extra investment costs for improved type

4,600,000 − 1,200,000 = 3,400,000 •

Annual savings for improved type

10,800,000 − 3,600,000 = 7,200,000 •

Simple payback period = Investments / annual savings

3,400,000 = 0.5 years 7,200,000 = 6 months This means that in less than a year the money invested is recovered. In 5 years, over UGX 50,000,000 (fifty million) can be saved from this 2-pot stoves.

4

Data from a school that switched from traditional stoves to institutional rocket stoves x

PART 1 The Fixed Institutional Rocket Stove

Photo 1: A fixed Institutional Rocket Stove in use

1

2.0 Things to Consider Before Building the Institutional Rocket Stove 1. Shelter Ensure that a shelter is in place to house and protect the stove from intrusion and unfavourable weather conditions e.g. rain. 2. Tools The institutional rocket stove has two components: i.

The brickwork

ii.

The metal work

The common building construction tools are required for the brickwork while metal fabrication tools are required for the metal work.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Brickwork tools Hoe Pick axe Shovel or Spade Jerry can Sieve Trough (karaayi) Trowel Measuring Tape Spirit level Plumb line Try Square Building line Wooden float Claw Hammer Sledge Hammer Wall Chisel Bow Saw

Purpose Digging foundation base and mixing ingredients Digging foundation base Extract soil from foundation base and mixing ingredients Fetching water Sifting ingredients Measuring materials by volume and carrying mixtures Placing mortar and smoothing plaster Taking measurements Inspecting horizontal level for laid bricks Inspecting vertical level for laid bricks Inspecting right angled corners Inspecting brick layer levels Smoothing plaster Driving and removal of nails Driving foundation pegs into the ground Split, cut into, notch bricks and walls Slicing pumice into regular shaped slabs

2

1 2 3 4 5 6 7 8 9 10 11 12

Metal fabrication Tools

Purpose

Hacksaw Vice Hammer Chisel File Measuring Tape Try Square Anvil (or equivalent) Arc welding set Pick hammer Angle grinder Wire brush

Cutting sections to length Holding sections when being cut to length Driving chisel Cutting metal sheet Smoothing metal edges Taking linear measurements Inspecting right angled corners Base for hammering ing metal pieces Removes slag from welded metal parts Smoothening the welded ts Cleaning metal surfaces prior to welding

3. Safety Gear5 1 2 3 4 5 6 7 8 9

Device Eye Shield Leather gloves Leather apron Nose Mask Industrial boots Helmet Overalls First Aid Kit6 Eye goggles

Purpose Protection of eyes against radiation during welding Protection of hands from fire during welding Protection of body and clothes during welding Protection against inhaling of toxic gases during welding Protection of feet during welding Protection of the head during welding Protection of clothes during welding Treatment for injuries Protection for the eyes e.g. when grinding

2.1 Stove Construction Materials The quantities below are estimated for a stove of dimensions 140 x 140 x 116cm accommodating a saucepan of capacity 250 L. For other sizes saucepans, the quantities can be adjusted accordingly.

5 6

Recommended for use where available Professional workshop practice recommends that a First Aid kit should be in place. 3

2.2 Brickwork N 1 1.1 1.2 1.3 1.4 1.5 1.7

ITEM Brick Structure Bricks Curved Bricks Sand Sand Cement Water

2 2.1 2.2 2.3 2.5 2.6 2.8

SPECIFICATIONS

QUANTITY

12 X 12 X 22 cm, Fired clay Hollow, Semi circular, Fired clay Lake Sand River Sand OPS / PPS

600 140 0.5 0.5 6 25

Ton(s) Ton(s) Bag(s) =@ 50kg Jerrycan(s) @ 20 Litres

Heat Insulation Pumice Fire cement

Porous

1.5 1

Sack(s) @ 100L bag

Grog Fire bricks7 Vermiculite Quarry

High Temperature Mixture (HTM) High Temp (4”x3”x9” Kajjansi) Exfoliated 8 x 12 X 2”, Fired clay

4 30 3.5 10

bags Sack(s) @ 100L Pc(s)

2.3 Metalwork ITEM

SPECIFICATION

QUANTITY

1

Stove Frame

Angle section (40X40X3mm)

1

Pc(s)

2

Grate

Cast iron (1.5”X10X10mm)

2

Pc(s)

3

Ash scoop

Mild steel

2

Pc(s)

4

Saucepan ring/stabilizer

1

Pc(s)

5

Saucepan

Ø 12mm X 6m 250L 3mm bottom, 2mm side (stainless steel- human food grade)

1

Pc(s)

6

Saucepan lid

Aluminium/ stainless steel(human grade) type

1

Pc(s)

7

Welded mesh

4X8” G10

1

Pc(s)

8

Chimney

Galvanised 5.5” G24

1

Pc(s)

2.2 Material purchase Purchase the stove brickwork construction materials and deliver them at the stove construction site. Caution: 1. Materials like vermiculite, pumice, cement, sodium silicate and wall tiles are expensive and should be stored in a secure room. 2. Cement, vermiculite, pumice and sodium silicate should be kept in a dry place

7

These can be replaced by the fired clay liners of appropriate dimensions 4

3.0 Stove Planning 3.1 Mapping out the stove position Choose a corner in the kitchen to be occupied by the stove. This will minimise the possibility of accidental damage and it will also be useful in preventing the stove from direct intake of cold air.

Figure 1: stove positioning

3.2 Determining the stove base dimensions •

Using the largest pot diameter used for cooking in the institution, the width of the combustion chamber is determined from the table in the appendix. E.g. for a 250 L saucepan with diameter 84 cm the chamber width is 24 cm.

•

The combustion chamber cross-section area, height and size are read from the same table (i.e. A=576 cm2, H=60 cm, K=36 cm).

•

Add 2X2 cm to the saucepan diameter to obtain the inner diameter for the curved bricks structure/ assembly.

•

Add 2X10 cm for the width of the curved bricks’ width. (assumed when 10 cm curved brick)

•

Add2X6 cm for the insulation width.

•

Add 2X10 cm for the outer wall bricks. (assumed when 12m wide selected bricks finish)

5

This gives the minimum width of the stove. In our example therefore, the stove width, W=84+4+20+12+20=140.

140 Outer wall

140

6

10

Saucepan diameter = 84 cm

10 cm round brick

10

Figure 2: Stove plan dimensions

The base area of the stove, for instance, will be about 140X 140cm, when built to accommodate saucepans of diameter 84 cm. In case of ordinary (local) bricks of varying dimensions, the stove width and length should be varied to taking into consideration the brick sizes.

6

B The Fixed Instituional Rocket stove Ø14 Capacity:250 Litres Fuel: Firewood Dimensions: cm Designed by: GTZ - PREEEP Drawn by: Job Mutyaba Date: June 2008

Ø108 Ø88

Platform

Angle frame

A

A

Stabiliser bars Saucepan Lid

Top Finish 5

B

35

44

Saucepan

PLAN VIEW 84

14 Chimney

7

10

88

43

116

38

Firewood Magazine

15 30

Air inlet 140 Section A-A

7

Air inlet 10

35

14

22

14

35

10

Section B-B

Figure 3: Technical diagrams of the stove 7

3.3 Obtaining the length of the combustion chamber (L) ¾ Draw the outline of the stove base on paper with dimensions clearly marked ¾ Following these drawings, make a floor plan where the stove is to be built. ¾ Mark off the centre of the fuel magazine opening. ¾ Draw the diagonal lines across the outline and mark where they cross each other as shown in figure 4. ¾ Measure the distance between this point and the centre point of the stove fuel magazine opening. ¾ This gives the distance from the opening to the centre of the combustion chamber (b). ¾ To b add a half of the stove width 1 2 J . ¾ This gives the total length of the combustion chamber fuel magazine. i.e.

L = b + 12 J

W

Figure 4: Locating the combustion Chamber

8

4.0 Preparation of materials Prepare the construction materials for the stove as described below. 4.1 Preparing the mortar; 4.1.1 Using the sieve, the sand to

sift

obtain fine

granules. 4.1.2 Mix the sand and cement, in the volumetric ratio 3 : 1 4.1.3 Blend the mixture to homogeneity. 4.1.4 Slowly add water to the mixture just to make it mouldable Photo 2: preparing mortar

4.2 Preparing the insulation mortar 1. The grog and cement are mixed in the ratio 2 : 1 2. Adding water, the mixture is blended to homogeneity using a shovel.

9

5.0 Building the stove Note: In case the stove is to be built in a kitchen with a concrete floor, skip steps 5.1 – 5.3

5.1

Mark out the foundation on the ground using a string, sticks or chalk, measuring tape and try

Photo 3: setting out

square 5.2

Excavate a foundation of 30 cm wide by 30 cm or more depth.

Photo 4: Digging the foundation

5.3

Lay the foundation by first wetting the ground with water, and then place some mortar and then bricks in the excavated space.

Photo 5: Construction of the foundation

10

5.4 Build the first course of the outer wall using either selected or ordinary bricks. Ensure that the air inlet and firewood magazine are planned for.

Photo 6: construction out on a concrete slab

5.5 The air inlet and firewood magazine are built using the fire resistant mortar and special firebricks/ clay liners. A grate is inserted in combustion chamber as shown Grate

Photo 7: Stove Building

in photo 7.

5.6

The combustion chamber wall is built using fire bricks. 6-7cm pumice insulation is placed surrounding the firebrick wall. A wall is built behind the firewood magazine to provide extra strength against impact of insertion of firewood.

Photo 8: Combustion chamber construction

11

5.7

Continue to build the walls of the combustion chamber using the fire bricks, maintaining the inside cross section as uniformly as required.

Photo 9: combustion chamber building

5.8

Raise the combustion chamber walls and the walls to the required height (H) as given in the table (appendix 1)

Insulation Insulation Photo 10: Insulating the combustion chamber

wall

Combustion chamber wall

12

5.9 Add a layer of mortar at the base of the space between the outer wall and the wall. Fill this space with debris up to about 5 cm below the combustion chamber level. Cover the debris with grog Photo 11: filling the stove body with debris

and cement mortar. Make sure to slant the mortar finish slightly downwards to the combustion chamber top.

5.10 Cut a mesh of length equal to the inner dimensions of the stove body. Photo 12: Centering the saucepan stabiliser

5.11 Cut out a provision for the combustion chamber. 5.12 Using diagonally fixed strings, the centre of the combustion chamber is located. Place the saucepan stabiliser onto the stove and centre it.

Photo 13: The saucepan stabiliser

13

5.12

Using the insulation mortar, build the circular brick wall up to the top. Replace the saucepan several times to ensure the 2 cm gap is maintained. to leave a brick space in the last course of round bricks for the chimney opening.

Photo 14: Construction of the saucepan skirt

5.13

Note: The saucepan stabiliser should be levelled before further construction.

5.14

Fill the gap between the inner round brick wall and the outer wall with insulation (vermiculite and/or pumice)

5.15 Photo 15: The provision or the chimney

Fix the chimney before setting the top slab

14

6.0 Finishing the stove

Chimney

6.1 6.1

Place a wire mesh around the Fix the chimney (see photo 16) saucepan ring. Fix the chimney and make the top slab. Allow the (see photo 16) and make the top slab to set before making the slab. Allow the slab to set before stove finish. making the stove finish.

6.2

Cover this with grog and cement mortar. It should extend all over the brickwork. Give it a smooth finishing, slightly slanting outwards.

Photo 16: Fixing the chimney pipe

Weld the angle section into a frame to fit the outer edges of the stove. Fit this frame on the stove inserting it into the ground. This will protect the stove edges from damage Photo 17: A slab on top of the stove

6.3 If terrazzo was used as a slab on the top surface, after 1 day it should be grinded with an angle grinder.

Photo 18: Grinding a stove with a terrazzo finish

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PART 2 The Mobile Institutional Rocket Stove 1.0 Things to consider before building the Mobile Institutional Rocket Stove 1.1 Shelter Ensure that shelter is in place to house and protect the mobile Institutional rocket stove from intrusion and unfavourable weather conditions e.g. rain. 1.2 Tools For the most part, the stove is metallic therefore metal fabrication tools are required for the metallic components. For bonding purposes cement mixing tools are required.

1 3 4 5 6 7 8

Mortar mix tools Hoe Shovel or Spade Jerry can Sieve Trough (karaayi) Trowel Bow Saw

Purpose Mixing ingredients Mixing ingredients Fetching water Sifting ingredients Measuring materials by volume and carrying mixtures Placing mortar and smoothing plaster Cutting pumice into regular shaped blocks

1 2 3 4 5 6 7 8 9 11 12

Metal fabrication Tools Hacksaw Vice Hammer Chisel File Measuring Tape Try Square Anvil (or equivalent) Arc welding set Sheet metal rolling equipment Pick hammer

Purpose Cutting sections to length Holding sections when being cut to length Driving chisel, removing of slag Cutting metal sheet Smoothing metal edges Taking linear measurements Measuring right angles Base for hammering ing metal pieces Rolling the sheet metal Removing slag from welded ts

16

1.3 Safety Gear

1 2 3 4 5 6 7 8 9

Device Eye Shield Leather gloves Leather apron Nose Mask Industrial boots Helmet Overalls First Aid Kit Eye goggles

Purpose Protection of eyes against radiation during welding Protection of hands from fire during welding Protection of body and clothes during welding Protection against inhaling of toxic during welding Protection of feet during welding Protection of head during welding Protection of clothes during welding Treatment for injuries Protection of eyes

2.0 Stove Planning (The quantities below are estimated for a stove whose saucepan capacity is 100L. For bigger saucepans, the quantities can be adjusted accordingly.) 2.1

Bonding and insulating

1 2 3 4 5 6

ITEM Cement Water Pumice Sodium Silicate Vermiculite Quarry tiles

2.2

Mobile rocket institutional stove fabrication

1 3 4 5 6 7 8

ITEM M.S. Plate Angle bars Firewood shelf Welding rods (1 pack) Rebar Flat section Flat section

SPECIFICATION Portland Porous Liquid Exfoliated

QUANTITY 1 Bag 2 Jerry cans (@ 20 L = 40L) 1 bag (@ 100 L) 10 L Jerry can ½ Bag

SPECIFICATION 4’ x 8’ x 2 mm 40X40X3mmX6m Steel Fabricated G.10 ½ “. x 40mm x 12.7 mm 4 mm x 50 mm 4 mm x 25 mm

QUANTITY 2 Pcs 1 Pc 1 Pc 1 Packet 1 bar 2 bars 1 bar

17

2.3 Purchase and delivery Purchase the mortar constituents and deliver them at the site. Note: cement, vermiculite and pumice should be kept indoors in a dry room. Materials for metal fabrication should be delivered to a metal fabrication workshop. The metal work fabrication will be dealt with at a later stage. 2.4 Stove Assembly The Mobile institutional stove is made up of largely two main parts (see diagram below) namely: 1. the saucepan skirt and 2. the combustion chamber. In the construction of the stove these two main parts are the main areas of focus. Other parts include: 1. firewood shelf 2. handles

Fig 5: A representation of the institutional mobile stove

18

2.5 Stove Sizing The size of the stove is determined using the size of the saucepan that will be used for cooking in it. The saucepan capacity is therefore the first thing that should be determined. Below are the step taken in planning the stove parameters 1. Determine the saucepan capacity in litres 2. Measure the saucepan diameter at different points on the top and bottom of the saucepan. Use the largest saucepan diameter as the value, d. 3. From the table at the end of this manual, read combustion chamber values J, K, H for the given saucepan capacity 4. Determine the saucepan skirt diameter D, Outer cylinder diameter D1 and P following the simple calculations from the table below. Measurement Key

Denotation

Saucepan diameter

d

Saucepan Skirt

D=d+4

Overall Diameter

D1=D+5

Saucepan skirt height

P

(See appendix for more) For example, if D = 63 cm Saucepan skirt diameter= D + 4 = 67 cm Overall diameter = D + 4 + 5 =72cm Note: To minimise wastage of metal, ensure that proper planning is done.

19

3.0 Main Parts of the Mobile stoves 3.1 The saucepan skirt The Saucepan skirt (figure 6) houses the saucepan during cooking. It is made of an outer and inner metal sheet. Vermiculite or any other appropriate insulation is put between the two circular sheets and the assembly is sealed off with a top ring (figure 9).

D

P

Figure 6: The saucepan skirt

3.2 Combustion chamber block (with an air by)

Clay liner

Firewood magazine

Air inlet

Figure 7: A combustion chamber block with a separate air inlet

20

3.3 Base plate This circular plate (figure 8) forms the base of the saucepan skirt. Onto it, the skirting, the stove stands and the saucepan stands are welded. It is also welded to the combustion chamber box so that the flames and hot gases through the square opening found in the centre of the base plate.

D1

Combustion chamber position/slot

Figure 8: A base plate with a square hole for the combustion chamber

3.4 The stove/saucepan stand assembly

21

3.5 Top Ring

d2 The top

d1

Figure 9: The diameters d1 and d2 of the top ring

The top ring covers the insulation material in the saucepan skirt. d1 and d2 are inner and outer diameters respectively

22

3.6 Stove Technical Drawing

Figure 10: A sliced section showing the different parts of the mobile rocket stove

The third angle orthographic projection views of the stoves, on the next page, were developed by GTZ - PREEEP to aid in visualisation of the stove.

23

B

A

The mobile institutional stove

A

Capacity: 100L Dimensions: cm Design: GTZ - PREEEP Drawn by: Job Mutyaba Date: June 2008 Ø72.0

B

Ø67.0

Plan View

67.0 Vemiculite 45.0 20.0 Clay Liner & Insulation 23.0 Grate

12.0 Firewood

Section A-A

50.0

Firewood Magazine

32.0 Air inlet

Section B-B

Figure 11: Technical diagrams of the mobile institutional rocket stove 24

4.0 Fabricating the stove 4.1 The outer skirting -

Lay down a mild steel (MS) plate of 4’x 8’x2mm (122x244x0.2cm).

-

Measure and mark off a rectangle of Length (π x D1) and width, P on the sheet metal.

-

If it is not long enough, measure off the required additional piece from another similar metal sheet (sheet 1). Mark off rectangle of length π * D by P. (Sheet 2) e.g. for a 100L saucepan, Length =

Photo 19: Marking off measurements

230 cm and Width = 40 cm -

Use an angle grinder with a metal cutting disc to cut off the marked sheets 1 and 2

-

Alternatively the metal sheets could be cut with a hammer driven chisel

Photo 20: Metal cutting with an Angle grinder

-

Using a metal roller (3- roll), curve the metal sheets as shown

Photo 21: Metal rolling

25

Note: Alternatively, the metal sheets can be rolled manually using an I-beam

Photo 22: Metal rolling with simple hand tools

-

Weld the edges of the curved metal together to form a cylinder.

Photo 23: Welding the rolled metal sheet

Photo 24: A finished saucepan skirt in cylindrical shape 26

4.2 The inner cylinder This one is fabricated in a similar manner as that of the outer cylinder. From the drawings, for 100 L saucepan, D = 67 cm, L = 40 cm E.g. for 100 L stove, The length of plate will be π X D = 3.14 X 67 cm = 210 cm Width of plate will remain 40 cm 4.3 The combustion chamber block

-

Take measurements from the metal sheet and cut out all sides of the metal box.

-

Weld the cut pieces of the combustion chamber block together.

Photo 25: Marking off dimensions for the combustion chamber

4.4 Base Plate

-

Using chisels or any other appropriate cutting tool, cut out a circular piece of diameter D1+2. Bend the ends using a hammer to make a 2cm vertical fold.

-

Insert the outer cylinder into the base plate so that the outer cylinder sits in the curved part

Photo 26: Bending a base plate

of the base plate

27

4.5 Stove assembly -

Weld the base plate onto the outer cylinder as shown.

Photo 27: Welding the outer cylinder onto the base plate

-

Cut out the slot for the combustion chamber in the centre of the base plate

-

The combustion chamber box is then welded onto the stove skirts

-

-

Photo 28: Using an angle grinder with a metal cutting disc to cut out a hole in the base plate

Cut out slots into the base plate through which the stands are inserted. Angle lines (40X40X3mm) or square hollow sections (40X40mm) can be used. The framework of the stove stands should be reinforced with cross , appropriately fitted to aid the stability of the stove.

28

Saucepan stands

120o

-

Note: the saucepan stands also double as the stove stands. The size and shape of the slots will depend on the cross-sectional area and shape of the stands respectively.

-

From a flat metal sheet, cut out the top ring that is illustrated in figure 9 on page 30 Cut a flat section of width 5cm and length equal to the circumference of the outer diameter (π X D1) Curve it to form a cylindrical shape and weld it along the outer diameter of the top ring

D1

Figure 12: Positioning of the saucepan stands

-

-

Photo 29: Making a top ring

Handles Use a 12 cm diameter round bar to make the handles. The total length of the bar for two handles is 96 cm.

29

16cm

9cm

7cm

Figure 13: How to make the stove handles

4.6 Stove insulation -

Prepare the insulation mortar in the volumetric ratio cement : grog as 1 : 2

-

Add water and use a spade to mix to thoroughly.

Figure 14: A Clay Liner8 for a 100 L institutional stove

8

Liners should be made by a qualified industrial ceramist. They should have insulation properties and must be abrasion resistant. 30

-

Clay liners are fitted into the combustion chamber box. The liners are bonded to the combustion chamber box with grog mortar.

Photo 30: Using grog to bind the combustion chamber box with the liner

-

Note: When quarry tiles are used, they should be lined along the entire combustion chamber to protect the chamber from abrasion while in operation. Pumice blocks are used to insulate the stoves while tiles protect the pumice from wear due to abrasion.

-

In this case, cut the pumice into slabs of 5 cm thickness. Size them to fit in the combustion chamber box. Use the mortar to bond the pumice to the metallic wall and to the quarry tiles.

Photo 31: The inside of a chamber with an insulation slant set onto the bas plate

-

Cover the base plate with a thin layer of pumice making a slant such that the height above the slant from at the end of skirt is not less than 1cm when measured from the saucepan base

31

-

Bond the pumice with the insulation mortar (cement, grog and water).

-

Use the insulation mortar to cover and smooth the slants.

-

Smoothen using a trowel.

-

Grind all sharp edges of the metallic stove body to make it smooth.

-

Clean the metallic stove body with a wire brush to remove dirt and rust. Paint the stove to protect the steel body from rust etc.

32

Fig 15: A finished institutional mobile rocket stove

33

Appendix: Relationship between Saucepan / Pot Diameter and Combustion Chamber J J

A K

2J/3

K H

H

2J/3 2J/3

D

J

J

J 3

J 3

The rocket elbow combustion chamber

38

Chamber Area (cm2) 225

Chamber Sizing (cm) 15 x 15

24

40

256

16 x 16

18

27

45

324

18 x 18

81-100

20

30

50

400

20 x 20

101-150

21

32

53

441

21 x 21

151-200

22

33

55

484

22 x 22

4

201-230

23

35

58

529

23 x 23

5

231-300

24

36

60

576

24 x 24

Notation

Pot Capacity (L)

J (cm)

K = 1.5 X J (cm)

H = K + J (cm)

20-40

15

23

41-60

16

61-80 1 2 3

34