Presentation on theme: "Titiladunayo, Isaac Femi Department of Mechanical Engineering"— Presentation transcript:
1 Titiladunayo, Isaac Femi Department of Mechanical Engineering DEVELOPMENT OF A BIOMASS PYROLYSIS REACTOR AND CHARACTERISATION OF ITS PRODUCTS FOR INDUSTRIAL APPLICATIONSTitiladunayo, Isaac FemiDepartment of Mechanical EngineeringThe Federal University of Technology Akure. Ondo State. NigeriaJANUARY, 2012
2 IntroductionIt comprises:- aggregate of all biologically produced matter inform of:wood and wood wastes;agricultural crops and their waste by-products;municipal solid wastes;animal wastes;wastes from food processing;and aquatic plants including sea weeds and algae (Agarwal and Agarwal, 1999; U.S Dept of Energy, 2003).Biomass is cheap, available, affordable and reliableIt’s a regular source of rural energy in Nigeria, fuel wood is cheap, easily accessed by both rural & urban dwellers.
3 Introduction Biomass – renewable, available, and abundant on earth. It is a versatile energy and chemical resourceIt could be converted into renewable products that could significantly supplement the energy needs of society
4 Introduction Cont.---Globally, 140 billion metric tons of biomass is generated every year from agriculture.This volume of biomass can be converted to an enormous amount of energy and raw materials, equivalent to approximately 50 billion tons of oil.Agricultural biomass waste converted to energy can substantially displace fossil fuel, reduce emissions of greenhouse gases and provide renewable energy to some 1.6 billion people in developing countries, which still lack access to electricity.As raw materials, biomass wastes have attractive potentials for large-scale industries and community- level enterprises (UNEP 2009).The United Nations Environment Programme (UNEP)
6 Biomass Resource & Availability Cont... Municipal Solid Wastes (MSW): generation is enormous in our society.The expanding urban centres in Nigeria have tremendous production of solid wastes that could be utilized for energy through different conversion routes. Garbage wastes due to human & animal activities are massiveLagos with 18 million inhabitants generates about 9,000 metric tons of municipal solid waste daily (0.5 kg/person/day), 80 percent of this waste can be reconverted (LAWMA, 2010). Ibadan: 0.37–0.5 kg/person/day (Maclaren International Ltd, 1970)
7 Fig.2: Ojota dumpsite, Lagos, Nigeria. (Courtesy: LAWMA, 2010)
8 MSW - Material Distribution Composition of MSW – Variable50% Lignocellulosic Mat.(Wood, paper etc)15% synthetic polymer based materials- Polyethylene (PE), Polypropylene (PP) and Polyvinylchloride (PVC)20% inorganic materials (metals, glass etc)15% others (Blasi, 1997)Natural Decomposition- May affect environment & climate changeRecycling waste for energy and chemicals products will consume waste and safe the environment
9 Straws and Grasses for Energy Rice StrawMiscanthusFig.3: Straw and Grasses
10 Wood compositionSoftwoodHardwoodCellulose content42% +/- 2%45% +/- 2%Lignin content28% +/- 3%20% +/- 4%Extractives content3% +/- 2%5% +/- 3%Fibre length2-6 mmmmCoarseness15-35 mg/100 mm5-10 mg/100mCellulose and hemi-cellulose contain only around 17.5 MJ/kg high heating values (HHV) while lignin has about 26.5 MJ/kg HHV and extractives can approach 35 MJ/kg HHV(Ramachandra and Kamakshi, 2005;NC State, 1993
11 Polymeric Constituent of woody Biomass 1. Cellulose (C6H10O5)n •Structure, fibre walls •Carbohydrate (sugar) •Polymer of glucose C6H10O6 2 Hemicellulose(C5H8O4)n •Encasing of cellulose fibre •Carbohydrate •Other than glucose •Dissolvable 3 Lignin (C40H44O6) •Binding agent / strength •Non-sugar polymer •Aromatic structure
13 Particle size Preparation Process: Chipping, grinding and milling to reduce particle size.Materials size after chipping –30 mmSize after milling or grinding –2 mm.Type of milling M/C:(i) Vibratory ball milling(ii) Ball milling (Millet et al.,1976)
14 Biochemical biomass Conversion Fermentation is the biochemical route of converting sugar, starch or hydrolysed lignocellulosic biomass to ethanol (alcohol) in a process similar to anaerobic respirationMilling to an optimum size to facilitate effective pretreatment.Pretreatment to facilitate effective Hydrolysis and fermentation.Hydrolysis - conversion of cellulose to sugarsFermentation of sugars to bioethanol.Filtration and/or distillation to remove the byproducts from the bioethanol.Management of Waste by-product.Bioethanol & Biogas production –Root, tubers, grains, seeds, manures,etcBiodiesel production from oil seeds, fruits, sunflowers etc.
16 Biomass Energy Conversion Routes: Direct Combustion: Exothermic reaction of biomass combustible elements with Oxygen.Biomass locked-up energy is released by burning.The combustible elemental composition of biomass is completely oxidized to H2O & CO2 with the release of heat and light (FAO, 1987).requires adequate air supply;Carbonization is the energy conversion process undertaken with the intention to maximize the production of char at the expense of other pyrolysis products. The basic reaction in wood carbonization involves the expulsion of water from its cellulose structure, thus maximizing its carbon percentage.
17 THE PYROLYSIS PROCESS: Carbonisation: Upgrades biomass energy to high dense energy fractions in a quiescence environmentThe three major biomass polymer building blocks degrades to charcoal, pyroligneous liquor and syngasProcess is influenced: heating rate, residence time, particle size, chemical composition, moisture content and final pyrolysis temp. of the wood feedstock.
18 Reaction Temperatures Effect of temperature on biomassAt a temperature less than 260ºC Charring of biomass feedstock occursBetween 275ºC and 400ºC depolymerisation of chemical components generally predominatesBetween 200ºC and 280ºC hemicellulose is converted to methanol and acetic acidAbove 280 ºC lignin decomposes to produce tar and charcoal (Hillis, 1975; Bailey and Blankehorn, 1982; Fuwape, 1996).
20 Economic Advantage of Biomass Energy Utilizing forest residues, mill residues, logging residues and various wood cuttings for charcoal production will go a long way to boost domestic and industrial energy resources, thereby reduce pressure on the forest.Inexhaustible production of renewable fuel & chemicals is guaranteedIt improves the environment, as waste is consumed & the effect of Methane is mitigatedWood conversion to charcoal is a process involving the thermal separation of its volatile constituent from the char residue.
21 Economic Advantage of Biomass Energy Charcoal is a high-grade fuel having a heating value of MJ/kg compared to wood of MJ/kg (Fuwape, 1996).Charcoal is easier to handle than the parent stock,Fuel for household and industrial settings (metal extraction in iron smelting, generating producer gas, serves as activated carbon particles for water treatment systems) (FAO, 1985).Pyroligneous oil is used as fuel oil substitute, chemical sources, solvent and insecticide
22 Industrial Utilization of Charcoal Chemical Industries - manufacture of carbon disulphide, sodium cyanide and carbides, ethanol, methanol, Acetic acid, etcIron Smelting - smelting and sintering iron ores, production of ferro-silicon and pure silicon, case hardening of steel, etcFuels - fuels in foundry, cupolas, electrodes in metallurgical industries, etcWater and Gas Purification - dechlorination, gas purification, solvent recovery; waste water treatment, etcGas Generator - In the production of producer gas for vehicles and carbonation of soft drinks.
23 Charcoal as fuel for industry The advantages of charcoal depend on six significant properties which account for its continued use as fuel in industry.relatively few and unreactive inorganic impuritiesstable pore structure with high surface arealow sulphur contenthigh ratio of carbon to ashgood reduction abilityalmost smokeless
24 Pyroligneous LiquorCrude condensate consists mainly of water and non-water component:Crude bio-oil is dark brown and approximates to biomass in elemental composition.It is composed of a very complex mixture of oxygenated hydrocarbons with an appreciable proportion of water from both the original moisture and reaction product. Solid char may also be present. The liquid has a distinctive odour - an acrid smoky smell, which can irritate the eyes if exposed for a prolonged period to the liquids. The cause of this smell is due to the low molecular weight aldehydes and acids.Crude pyrolysis liquid or bio-oil is dark brown and approximates to biomass in elemental composition. It is composed of a very complex mixture of oxygenated hydrocarbons with an appreciable proportion of water from both the original moisture and reaction product. Solid char may also be present. The liquid has a distinctive odour - an acrid smoky smell, which can irritate the eyes if exposed for a prolonged period to the liquids
25 Properties of Pyrolysis oil (i) Oxygen content – 50 wt%(ii) Identified compounds(iii) Water Content – 30wt%(iv) LHV MJ/kg(v) Density (ρ) – 1.25 kg/dm3(vi) pH-value(vii)Molecular Weight g/mol(viii) Volatility Boiling Start 100°CResidues left (5-50 %) Stop °C(Czernik & Bridgwater, 2004; Oasmaa& Stefan, 1999)Density for Diesel oil/gas (ρ)= kg/dm3, Heating Value = 60% Diesel.
26 Non- Condensable gas (Syngas) Wood gas is useable as fuelIt consists typically of:17% methane;2% hydrogen;23% carbon monoxide;38% carbon dioxide;2% oxygenand 18% nitrogen.It has a gross calorific value of about MJ/m³ (290 BTU/cu.ft.) i.e. about one third the value of natural gas.Source: FAO (1985)
27 Inorganic Constituents of Ash Ash is a good source of calcium, potassium, phosphorus, magnesium, Sodium, Iron, Zinc, silicon, Copper and aluminium.Ash from woody biomass, in general, stimulates microbial activities and mineralization in the soil by improving both the soil's physical and chemical properties (Soil amendment).Wood ash neutralizes soil acidification caused by whole-tree harvesting as well as acid depositions (raise the pH of acidic soils)
28 The Pyrolysis PlantA pyrolysis plant is developed to produce higher dense energy products from renewable biomass through thermochemical conversion processes.The plant does not produce useful energy directly.More convenient high grade energy & chemical products, are produced under regulated heat load and restricted air supply.
29 Slow and Fast Pyrolysis Temperature = Low/ModerateHeating Rate = Low/HighCarrier gas = Not required/ RequiredMaterial Residence time = Long/shortVapor Residence time = Long/shortParticle size = ≥ 10cm / ≤ 1mmOil yield = Could be low/ High (70-80%)
30 Pit Mound (Liberia) Beehive kilns (USA) Biomass Charcoal Production TechniquesPit carbonisation methodKiln carbonisation methodThis method is termed; charcoal burning, as part of the wood charge is burnt to supply the needed heat for the effective transformation of the remaining wood charge to charcoal.Pit Mound (Liberia)Beehive kilns (USA)FAO, 2008FAO, 2008Fig.4: Kilns
31 Retort Processes:The retort process (destructive distillation of wood) came into industrial use in the 18th and 19th century (Fapetu, 2000).Heat for carbonisation in this process is externally supplied to a closed vessel, which contains the woodchips to be carbonised (FAO, 1987).Volatiles are captured and collected through various cooling or condensation devices.Pyrolysis in the kiln and retort devices occur in three notable phases: drying, pyrolysis, & cooling for the products of biomass.
32 The retort principle for carbonization (FAO, 2008) (B) Beehive kilns in Canyon Creek, Wise River Ranger District, Montana (USA)(C) Multiple hearth kilnA continuous rotary retortLambiotte Retort (France)Fig.5: Retorts
35 Biomass Thermal Degradation Cont.. Percentage charcoal yield decreases with increasing carbonisation temperature.The percentage yield of combustible gases (Syngas) & pyroligneous liquor is a function of:carbonisation temperature& degree of biomass polymerisation.
36 Justification (What has been done) Several studies considered wood carbonisation from °C (Bailey & Blankehorn, 1982; Fuwape 1996; Gommaa and Mohed, 2000; Shinya & Yukiwko, 2008).Conversion of wood to charcoal is affected by the heating rate, residence time, particle sizes, chemical composition and moisture of the wood and the final pyrolysis temp. (Fuwape 1996).Traditional kilning techniques (yield charcoal usually in the range of 5%-20% of the parent stock) &Industrial / Modern retorting techniques(20%-30%) (FAO, 2008).Charcoal yield takes between 7-30 days in the traditional kiln (Sanabria & Paz, 2001; SINTEF Energy Research, 2010).
37 Justification (Need for Current Work) Need to investigate the effect of higher temperature on lignocellulosic biomass than previously reported.Development of a pyrolysis plant with a comparative edge at reducing carbonisation time, and improving carbon yield at elevated temperatures.Most research work by authors; focused on temperate wood species, a need therefore arises for the physiochemical characterisation of tropical wood species and their thermochemical by-products.The effectiveness of the pyrolysis plant at handling variety of biomass species is investigated. The relationship between biomass yield as a function of the degree of biomass polymerisation and temperature is established.
38 Scope of the Project Feedstock selection, sizing and preparation Development of an electrically fired, fixed-bed reactor with electronics accessories and equipped with a pyrolysis furnace with selected refractory lining.Feedstock selection, sizing and preparationExperimentation, Documentation and Data Analysis
39 OBJECTIVES Specific objectives: Main objective: to develop biomass pyrolysis reactor and characterise its products for industrial applicationsSpecific objectives:develop a thermochemical reactor, for the conversion of selected lignocellulosic biomass materials into high grade energy and industrial products;evaluate the effects of temperature on the degree of carbonisation of the solid products;determine the physio-chemical, thermo-chemical and the gross energy characteristics of the selected biomass and their derived fractions; andassess their suitability for industrial applications.
40 DEVELOPMENT OF THE FIXED-BED REACTOR Furnace developmentSelection of appropriate refractory clay materials for lining the furnace of the pyrolysis plant from four locations in Ekiti State: - Ikere Ekiti, Fagbohun Ekiti, Ishan Ekiti and Ara Ekiti.Fig .7: Kaolin (China Clay)
41 DEVELOPMENT OF THE REACTOR Cont…. Appropriate refractory clay selection as furnace lining was based on:Meeting known physical, chemical, and refractory standards;Ability to withstand thermal shock & very high operating temperature (1800°C) without thermal deformation.Non-reactive characteristics with pyrolysis products at elevated temperatures.Efficient thermal conservation
42 Table.3:Chemical Characteristics of Selected Clays Mean and Standard Deviation of chemical PropertiesS/NoClaySamples%Al2O3SiO2K2OCaOTi2OMnOFe2O3MgONa2OCr2O3LOI1A30.46±0.89a50.92±2.12bc0.33±0.05d0.19±0.01d1.88±0.02d0.01±0.01cd2.07±0.1d0.13±0.02ad0.04±0.02c0.02±12.18±0.02a2B18.75±0.5b53.90±3.55b3.30±1.58a0.72±0.03c2.29±0.14c0.03±11.80.±0.16b0.01ac0.09±0.01b.00b7.85±3C13.48±0.5c40.68±1.72d2.88±0.19c1.12±0.07b2.68±0.15ab0.15±0.02b25.55.±0.10±0.92ab0.06±0.01a10.78.±4D10.92±0.58d59.90±3.94a3.25±0.09ab1.90±0.16a2.76±0.19±0.02a11.40±0.32c0.12a0.12±0.03a0.01bc7.98±0.01cA = Ikere-Ekiti, B = Fagbohun - Ekiti, C = Ishan -Ekiti, D = Ara -EkitiValues in the same column with different alphabet are significantly different from each other.(Result of Chemical test of Clays from selected sites in Ekiti State, Nigeria)
43 Physical Characteristics of Selected Clays Table.4: Mean and Standard Deviation of the Physical characteristic of the selected ClaySampleNoNameBulk densityg.cm-3Porosity%C.C.S.kg / cm2ShrinkageSlagResistanceAIKERE1.74±0.11d31.44±0.91a100±6.21c5.0±1.23aGoodBFAGBOHUN2.0±0.15a20.69±1.01bc140±6.44b2.0±.00bCISHAN2.0±0.02ab19.10±0.19d227±12.9a1.50±0.16bdPoorDARA1.99±0.01ac23.31±0.24b83±3.24d1.9±0.1bcA = Ikere-Ekiti, B = Fagbohun - Ekiti, C = Ishan -Ekiti, D = Ara –EkitiValues in the same column with different alphabet are significantly different from each other.
44 Pyrometric Cone Equivalent (PCE) Table 5 : Result of Refractoriness test on selected ClaysSampleNoSample NameRefractorinessPyrometric Cone Equivalent (PCE)SegerPCE No.Range / LimitTemperatureAIkereCone 29>1500°CHigh PCEBFagbohunCone 16<Intermediate PCECIshanCone 101300°CLow duty PCEDAra
45 The densities (ρClay) of the clay materials are functions of the major constituents of the (alumino-silicate ) refractory clay samplesPorosity is also a function of densityBulk density is highly significant in predicting the apparent porosity of the clay samples: R2 =
46 REACTOR COMPONENTSThe reactor : -Electrically–fired Furnace chamber-An airtight crucible (Fixed-Bed)-Control Box (With digital readout)- Step-down transformer- Counter-flow Liebig condenser- Pyro-oil traps- Gas displacement vessel- Cooling water circulation pump
47 THE FURNACE Developed from locally available materials Wall thickness was determined using:Appropriate heat transfer design tools in furnacesThermo-chemical and refractory properties of kaolin and the maximum designed furnace temperatureHeating rate was achieved by regulating the input voltage from the circuit’s transformer.Resistance (R1 and R2) of two heater elements connected in parallel, which is the equivalent resistance of the electrical connection in Fig (1) and (2).
48 HEAT INPUTR1VRR2R2FIG. 8: Resistance Elements Connected in ParallelReq
49 HEAT INPUT ContdThe total energy (Q) supplied to the furnace is obtained by substituting equation (4) into (3)
50 Ceramic wallFig.9 : Furnace WallHeat conduction through the furnace wall is obtained by applying the general heat conduction equation in cylindrical coordinate (Rajput, 2007; Yunus, 2002).
51 For steady state,for heat flow inradial direction and with no heat generation and equation (6) reduces to
52 Integrating equation (7) with boundary conditions of t = t1; at r = r1 and t = t2; at r = r2 the value for temperature distribution‘t’ within the furnace wall becomes:(8)Heat transfer rate is obtained by substituting equation (8) in Fourier’s equation (9) to give equation (10):(9)
53 (10)(11)By integrating equation (10)The Furnace appropriate wall thickness was obtained by substituting equation (5) in (11):(12)
54 Integrating equation (7) with boundary conditions of t = t1; at r = r1 and t = t2; at r = r2 the value for temperature distribution ‘t’ within the furnace wall becomes:Heat transfer rate is obtained by substituting equation (8) in Fourier’s equation (9) to give equation (10):By integrating equation (10)
55 DETERMINATION OF THE APPROPRIATE FURNACE WALL THICKNESS: The Furnace appropriate wall thickness was obtained by substituting equation (5) in (11):DETERMINATION OF THE APPROPRIATE FURNACE WALL THICKNESS:By integrating equation (12) Furnace appropriate wall thickness is determined to be:
56 Furnace is shown in Figure (10) Figure(7) Fig.10: Reactor’s sections & Modeling
58 DEVELOPMENT OF THE FURNACE Cont... FIG. 12: Furnace with Cover
59 DEVELOPMENT OF THE FURNACE Cont… FIG. 13: Furnace Showing Resistance Elements
60 DESIGN OF BRASS CRUCIBLE: The brass crucible is made of m brass plate rolled into an enclosed cylinder and designed to hold averagely about kg of the selected biomass samples for carbonisation at a time in the designed furnace. Length (L) of the crucible is assumed but the densities of the various biomass feedstock ( ) were used to determined the volume of the crucible after experimentation.Average density ( ) =() =(Average mass ( ) =) =) =Volume of cylindrical crucible (
61 Combining equations 14, 15 and 16 the radius of the crucible is determined by equation (17) (18)The furnace completely envelopes the crucible and supplies its pyrolysis heat through an electrical resistance heater. Heat diffusion to the crucible from the inner surface of the furnace is assumed to have taken place by conduction, since the environment is assumed quiescent and the space between them negligibly small.Heat flux (Q) across the crucible could be analysed by the following equation:(19)
62 FIG. 14: The Fixed- Bed Reactor’s Crucible BRASS CRUCIBLEFIG. 14: The Fixed- Bed Reactor’s Crucible
63 DEVELOPMENT OF THE FURNACE Cont… FIG. 15: Furnace and Reactor
64 Design of Automatic Control Box Automatic Control Box: Heat input regulation and temperature / residence time control were achieved through the operation of the designed Automatic Control Box shown on Figure 10 (a & b).
65 Design of Automatic Control Box Fig .16 A: Control Box Wiring Diagram
68 Feedstock selection, sizing and preparation Materials Sizing: 10 kg each of Apa wood (A. africana), and Iroko wood (M. excelsa) were processed into fine rectangular pin chip particles size of 10 x 10 x 60 mmwhile Palm kernel shell (E. guineensis), was processed by sieving and utilised as receivedMoisture removal The materials were subjected to moisture removal in the oven using ASTM: E (ASTM 2006) at 103±2°C for 24 hours and until constant weight was attained per sample after three consecutive measurements.
69 Feedstock selection, sizing and preparation The free moisture in the samples was therefore completely removed by this process, making them to attain identical moisture free platform. The average moisture totally expelled from the 20 batches per material sample (%) was determined using equation (20).Total expelled moisture content (% wt/wt) =(20)
70 Selected Feedstock Species (B)A. africana(A)M. excelsa(C)E. guineensisFig. 17: Sizing of Selected Feedstock for Pyrolysis Experiments
71 Experimentation and Documentation Carbonisation experiments were carried out at various elevated temperatures for all samples in the developed electrically fired ‘Fixed-Bed Reactor’ at pre-determined temps., ranging from 400°C to 800°C and at 100°C intervals.Fifteen batches (0.5 kg net weight per batch) each of the selected materials of constant moisture content were used as feedstock in 3 replicated experiments
72 Experimentation & Documentation Cont… By-products of pyrolysis:charcoal (solid fuel),oils (liquid fuel),and pyrogas (non-condensable gaseous products).Experiments were conducted under a quiescent environment (insufficient or complete absence of air).Feedstock residence time, furnace temp. and pyrolysis (reaction) temp. were recorded as displayed on the controllers and recorded every 5 min.