ijars 660 auth copy

International Journal of Applied Research and Studies (iJARS)

ISSN: 2278-9480 Volume 2, Issue 10 (Oct - 2013)

www.ijars.in

Manuscript Id: iJARS/660 1|

*Authors Copy; Restricted to Personal Use Only any manipulation will be against copy Right Policy @ iJARS Mon-

.ijesat.org 1

Research Article

Design and Fabrication of Biomass Briquetting Machine Authors:

1 Jadhav O. K. *, 2

Dhakne K. A.

Address For correspondence:

1, 2 Pune Vidyarthi Griha’s College of Engineering and Technology, University of Pune, India

Abstract- Biomass briquettes are a bio fuel substitute to coal and charcoal. They are used to heat industrial boilers in order to produce electricity from steam. The most common use of the briquettes are in

the developing world, where energy sources are not as widely available. There has been a move to the use of briquettes in the developed world through the use of cofiring, when the briquettes are combined with coal in order to create the heat supplied to the boiler. This reduces carbon dioxide emissions by partially replacing coal used in power plants with materials that are already contained in the carbon cycle. Manufacturers mainly use three methods to create the briquettes, each depending on the way the biomass is dried out. Although biomass briquettes are usually manufactured, biomass has

been used throughout history all over the world from simply starting campfires to the mass generation of electricity. The contribution deals with the technology of biomass briquetting into the solid high grade biofuel by screw extrusion machines. It is focused mainly on the theory of compacting tools for screw briquetting presses, their analysis, stress conditions and geometry. The main aim is analyzing of pressing screw geometry and determination process of its design. Analysis of force conditions on the screw is necessary for designed

geometry verification and for stress analysis. The determination process of the frictional power is instrumental to main power drive design. Knowledge of these processes is the base of the new tools research for screw presses, the increase of tools lifetime and the competitiveness of whole technology

Keywords: Screw extrusion, Screw briquetting machine, highgrade biofuel, screw presses

1. INTRODUCTION

Biomass is renewable source of energy, potentially sustainable and environmentally benign. They are the derived from

living plants, animal manures, waste products from the processing industries and other sources. They substitute for fossil fuel as energy (non-renewable) source resulting in a net reduction in greenhouse gas emissions. World production of biomass is estimated at around 146 billion metric ton per year .Huge volumes of agricultural residues and wood processing residues are not fully utilized. One of the major world crop, rice, has about 25% of the crop in the form of husk, which amounts to about 100 million tonnes of residues. On a small

scale, world production of groundnut is about 10 million tonnes of

which about 45% is shell. Although there are crops with both high

and low residue yields, it is reasonable to assume that about 25% of any dry agricultural feedstock is residue. Field residues are the major biomass, which could be utilized as feedstock for production of

briquettes, ethanol and gaseous fuels. For example, high yielding maize can produce field residues as much as 11 t/ha annually; a more likely yield in most developing countries would be 25 t/ha, with rice

being the highest yielder. Cotton crop produces 4 to 20 t~a annually. Process residues such as bagasse from sugarcane, coffee husks, groundnut shells, rice husk, coir dust, saw dust, furniture wastes, etc.

Can also be briquetted. Biomass has huge quantities of energy, which are derived during the process of photosynthesis. This renewable form of energy can be recovered by combustion process or by conversion of biomass into usable form such as ethanol, pellets/briquettes, bio-oils or producer gases. The net energy available from biomass ranges from 20 MJ/kg for dry plant matter to 55 MJ/kg for methane, as compared to coal with about 27 MJ/kg .Biomass have low bulk density. This causes major problem during storage, handling and transportation for further processing. The

lowest bulk densities are around 40 kg/m 3 for loose straw and bagasse; the highest levels are around 250 kg/m 3 for some wood residues. Thus, gain in bulk densities of 2 to 10 times can be expected from densification. Direct burning of unprocessed biomass for industrial applications is very inefficient. One of the strategies to overcome this is to densify them into pellets or briquettes, which also increases the volumetric energy content, reduces transportation cost and makes it available for a variety of applications .Densification

involves the use of some form of mechanical pressure to reduce the volume of biological matter, which is easier to handle and store than the original material. Densification ofbiomass is mostly called briquetting, when it is utilized for energy production. Densification of biomass for animal feed production is called pelleting and cubing.

2. DESIGN OF SCREW BY REVERSE ENGINEERING

The screw briquetting process consits of extrusion of the material by a screw extruder which acts as a continuous feeder. The volume of the material is decreased as it is transferred from the hopper to the die exit. This is achieved by increasing the root diameter of the threaded shaft gradually starting with a small diameter at the feeding position and increase gradually to a maximum value at the die position. Figure 4 shows the design of the screw. Due

to the limited manufacturing facilities at the location of the plant the screw manufacturing was the biggest challenge faced during the process. Making the extruder screw was really a big challenge when dealing with such a task in an environment of limited manufacturing facilities. The easiest method was found is to taper the shaft diameter from one

side into a conical shape and then grooving the thread base on the

shaft tapered surface, then welding a heavy steel plate to form the

thread. The thread height was made constant and of a value

[email protected] *Corresponding Author Email-Id

mailto:[email protected]



www.ijars.in



.ijesat.org 2

smaller by only a little clearance than the inner diameter of the barrel, this was conducted using a normal lathe turning operation.

The feed stock consists of the slurry mixture of the carbonized powdered cotton stalks and the binder. The briquettes were relatively moist when produced and required to be placed under the sun for drying before packing them for distribution.

Figure 1: Graph showing counter pressure (vs) length of the

briquette

2.1 Analysis of Vietnamese screw for reverse engineering.

Vietnamese briquetting machine consists of following Specifications. 1. A briquetting machine of Vietnamese design with gearbox for power transmission, a 15 HP electric motor, and a Vietnamese screw and die pairfor producing 71 mm diameter briquettes, 2. A coal/briquette-fired die-heaterstove, and 3. A smoke removal system (chimney type)

2.2 General specifications of screw

Motor: 15 hp; 1450 rpm 220/380V; 50 Hz Total length: 340 mm Length of threaded portion: 212 mm Screw speed: 200-240 rpm Weight: 3 kg Die-heater: 10.6 kW coal stove; can also use biomass briquettes.

Outer diameter of screw: 70 mm No. of screw thread: 4.5 Material: Mild Steel rod – 35 mm dia. Production rate: 75-90 kg/h Mild steel washer: 4 mm thick Raw materials: Ricehusk, coffee husk, saw dust

Die

Electricity consumption: 0.12 kWh/kg No. of grooves: 8 Width: 500 mm Length: 250 mm Tapered length: 75 Power transmission: Gear Box Internal dia - Front: 71 mm; Rear: 78 mm Weight: 400 kg

External dia - Front: 80 mm; Rear: 92 mm

Don’t exist many publications which described mathematical models including impact of individual structural

parameters. We did some analyses and we found two mathematical models which contains also structural parameters. Therefore we were able to test them a check their impact on other parameters in these models. The first mathematical model represents following equation PG = PK e (4λµH) /D

k .........................................................................(1)

Closer describing of the model you can find on Figure. This

mathematical model is describing compacting process on vertical press and is describing effecting forces and pressures in the pressing chamber. We tried to test the impact of length of compacted briquette H. From this result we will be able in future calculate the optimal length of pressing chamber. By testing we chose unit values for other parameters in model and step by step we raise the value of length of compacted briquette always about 10%. The results you can see in following. On the base of single-axis pressing theory in closed chamber we can analyze impact of length of pressing chamber

change. Diameter of pressing chamber with length of pressing chamber has significant impact on briquette properties at burning and also on pressing tool wearing. By burning of briquettes is needed slow combustion. This we can execute when the surface/volume ratio of briquettes is the smallest as can be. The same situation is also by pressing tools wearing. The pressing tool wearing is smaller when smaller surface/volume ratio of pressing tools is. Therefore is very significant to find the optimal geometry of pressing chamber

according to briquettes burning, to tools wearing and according to trade requests. Pressing conditions in closed chamber at single-axis pressing when is the counter pressure generated by counter pressure plug is shown in Figure 2. Maximal compacting pressure PK which is rising by pressing depend on pressing chamber length and shape; depend on friction relations between compacted material and wall of the chamber. Drag friction is backward assigned by radial pressure PR, applied to

chamber wall, by friction coefficient μ, and length of compacted briquette H. [Pm - (Pm + dPm)](πDk

2 /4)-µPRπDkdx = 0 .......................................(2) And Pk = Pg e (4λµH) /D

k .............................................................................(3)

Specifies relation between axial pressure pk and counter pressure effecting on compacted briquette pG. This mathematical model was designed by German researchers [1]. This mathematical model allows us to calculate the suitable length of compacted briquette, suitable counter pressure and suitable length of pressing chamber. With combination of friction coefficient and length of pressing chamber we can provide needed counter pressure at compacting. But how impact the length of pressing chamber and counter pressure the final

briquette quality represents by briquette density? Answer to this question can give us only the mathematical model which specifies relation between axial compacting pressure and briquette density. Therefore we designed the experiment for main influencing technological and material parameters evaluation. We tried to find functional dependence ρ = f (p, T, wr, L) …...........................................................................(4)



www.ijars.in



.ijesat.org 3

where: ρ – briquette density (kg.dm-3), p – axial compacting pressure (MPa), T – pressing temperature (ºC), wr – relative material moisture

(%) and L – fraction largeness (mm). We designed experimental pressing stand (see Figure) on which were executed experiment. This experimental stand allowed us to change the values of mentioned parameters and helped obtained suitable results for mathematical model designing.

Figure 2: Graph showing briquette density (vs) compacting pressure 2.3 Development of Experimental Setup 1. Screw development :

Basis of design : Estimation and assumptions

a. Final briquette density was 1000kg/m3, while at the inlet of hopper the bulk density of saw dust was about 250kg/m3, accordingly the compression was assumed to be 4 times and the initial pitch of thread, shank diametre was decided.

b. Compression was to be achieved in several stages, broadly compression in screw and maximum of compression in tapered barrel, accordingly the pitch and

the numbers of turns over the screw were fixed. c. Screw has a entirely new design. All the avalaible

litreature regarding the screw design was just a prerequisite.

d. Unlike the existing design of Vietnamese screw analysed by reverse engineering , this screw has a varying pitch with straight shank and straight outer diametre.

e. For cost cutting, screw was first turned on lathe with a

straight shank and then later washers were welded over it to form the helix rather than machining the entire as a single component.

2. Bearing selection: a. Depending on the screw shank the bearing was selected.

Bearing with housing with internal diametre 22 was selected and then the required load calculations were done.

b. TYPE: a. Deep groove ball bearing b.Thrust bearing

3. Development of straight and tapered barrel: After the screw and bearing design was completed, the outer barrel was designed. Keeping a minimum clearance between the outer diametre of screw and barrel surface the internal and outer diametres were fixed, also the length of barrel was fixed arbritarily.

4. Other avalaible components include Motor (1.44 Hp, 1440 rpm), gearbox (reduction 1:30), a 3ph electric supply.

3. ANALYSIS

As the major and the critical component of the machine i.e

the screw was developed by reverse engineering, analysis on any software was not done. The prototype was directly built up and tested for vibration ana;ysis, failure portions.

The following were the results observed after the trial run.

1. Initial washer thickness was 2 mm, due to very large pressure(130 Mpa) that was created the washers were crushed under stress.

2. The base structure was not rigid and the torque imparted to

the entire machine created a toppling effect over the entire assembly.

3. The material chosen by us was saw dust (bulk density being 250 kg/m3 ), however required compression ratio was not achieved.

4. The process required the need of a suitable binder in saw dust, the given sample of saw dust was tested for briquette formation on a standard coal briquetting machine but the efforts were in vain, the material in its original form did not

form briquettes. 5. Most of the compression was expected in the tapered

portion of the barrel, however material failed to transfer from the last screw thread into the tapering portion.

6. The motor power was insufficient (1.44 Hp).

3.1 Dealing with the problems

1. Washer thickness was increased from 2mm to 4mm . 2. Dead weight was added on to the base structure making it

more rigid. 3. Material was kept the same and machine oil was added to it. 4. Motor kept the same the number of revolutions were

changed (increased). 5. The taper angle was changed from 150 to 80.

4. FINAL MACHINE SPECIFICATIONS AND

ANALYSIS

1. Motor: 1.44 Hp; 1440 rpm 220V; 50 Hz 2. Total length of screw: 282 mm 3. Length of threaded portion: 152 mm 4. Screw speed: 50-55 rpm Weight: 1.8 kg 5. Outer diameter of screw: 52 mm

6. No. of screw thread: 6.5 7. Pitch reduction as- 30(2x)-27-24-21-18-16 (all in mm.

in 6.5 turns) 8. Material: Mild Steel rod – 54mm dia. 9. Mild steel washer: 4 mm thick

4.1 Cad drawings of actual fabricated components



www.ijars.in



.ijesat.org 4

Figure 3: Screw shank

Figure 4: Washer

Figure 5: Washers welded over the shank



www.ijars.in



.ijesat.org 5

4.2 Some actual photographs to support the drawings.

Photograph 1: Screw

Photograph 2: Assembly

Photograph 3: Washer

Photograph 4: Actual Briquette formed

Photograph 5: Briquette

5.RESULTS AND DISCUSSION

Thus analysis using software was not done here. The already existing Vietnamese screw was studied and the model was scaled down with a suitable factor. The photographs are clicked when the actual components were being fabricated. Entire process was based on trial and error. The dimensions were chosen of the components based on a safety factor and accordingly whatever changes had to be made after the trial run were made. Though by reverse engineering the varying pitch of the screw improved the

compression ratio and achieved the expected results in just a power of 1.44 Hp where on the other hand the conventional machines use 18-22 Hp. The screw can be termed as ‘conveying cum compression screw with a varying pitch’. If mass production is adopted of such smaller capacity machines, then these machines would be very cheaply available to the masses. The agrarian class can be benefited by this to a greater extent. A lot of waste is generated from agricultural activities, this waste can be effectively used in the

briquetting machines to generate briquettes, sold at the rate of Rs 30-40 per kg. It can be called as the best that is done out of waste. This would not only benefit the farmers economically but also serve as a

purpose to dispose off the degradable waste.



www.ijars.in



.ijesat.org 6

6. CONCLUSION

The use of biomass briquettes is strongly encouraged by issuing carbon credits. One carbon credit is equal to one free ton of carbon dioxide to be emitted into the atmosphere. India has started to replace charcoal with biomass briquettes in regards to boiler fuel, especially in the southern parts of the country because the biomass

briquettes can be created domestically, depending on the availability of land. Therefore, constantly rising fuel prices will be less influential in an economy if sources of fuel can be easily produced domestically. Lehra Fuel Tech Pvt Ltd is approved by Indian Renewable Energy Development Agency (IREDA), is one of the largest briquetting machine manufacturers from Ludhiana, India. In East Africa, work on biomass briquette production has been spearheaded by a number of NGOs with GVEP( Global Village Energy Partnership) taking a lead in promoting briquette products and briquette entrepreneurs in the three

East African countries namely Kenya, Uganda, and Tanzania. This has been achieved by a five year EU and Dutch government sponsored project called DEEP EA (Developing Energy Enterprises Project East Africa. The main feed stock for briquettes in the East African region has mainly been charcoal dust although alternative like sawdust, bagasse, coffee husks and rice husks have also been used. These briquettes find a wide use in gasifiers ( as a replacement to diesel), have a wide demand in hotels for heating purposes in ovens . A commercial approach is aslo

profitable if undertaken this on a large scale. This machine was particularly developed by us keeping in mind the material to be used (saw dust). If parametrs like :

1. Compression ratio 2. Bulk density of material 3. Avalaibility of biomass 4. Calorific value

Are altered and studied then even an universal machine can be developed which could handle varioyus types of homogeneous mixtrures and not specifically be binded to a single

REFERENCES

1. Tabil, L.G. Jr. and S. Sokhansanj (1996), "Compression and Compaction Behavior of Alfalfa Grinds, Part 1" Compression Behavior", Powder Handling and Processing, 8(1), pp. 17-23.

2. HORRIGHS, W., Determining the dimensions of extrusion presses with parallel-wall die channel for The compaction and

conveying of bulk solids, Aufbereitungs – Technik: Magazine, Duisburg,

Germany, 1985, No.12.

3. ASAE 368.4 (2006). Compression Test of Food Materials of

Convex Shape. St. Joseph, MI (USA): American Society of Agricultural and Biological Engineers (ASABE).

4. Eriksson, S. & Prior, M. (1990). The Briquetting of Agricultural Wastes for Fuel. Rome: Food and Agriculture Organization of

the United Nations, Publications Division.

*Authors Copy

ijars 660 auth copy

Documents