Analysis Soot Formation During Asphaltene Gasification Biology Essay

Global demand for energy is expected to increase 47 by 2035 as economic systems in both developed and emerging states continue to turn and criterions of life improve ( 1 ) . All beginnings of energy will be needed to run into growing in planetary demand. With conventional oil supply worsening, the demand for unconventional resources, like oil littorals, will increase. Canada has the largest oil militias in the universe after Saudi Arabia and 97 % of these militias are in the oil littorals. Harmonizing to Canadian Association of Petroleum Producers ( CAPP ) study Canada has 174 billion barrels of oil that can be recovered economically with bing engineering ( 2 ) . Of that entire oil, 169 billion barrels are located in the oil littorals. Oil sands by and large contain a mixture of sand, H2O, clay and bitumen. Bitumen is a constituent of oil that is excessively thick to flux or be pumped without being diluted or heated. Some bitumen is found within 200 pess from the surface but the bulk is deeper resistance.

Canada ‘s oil littorals are found in three of import basins – the Athabasca, Peace River and Cold Lake basins in Alberta. The two of import methods used for oil littorals recovery are surface excavation and boring ( in situ ) . The method applicable depends on at what depth the militias are deposited. 20 % of the oil sands sedimentations are close plenty to the surface, so that it can be mined utilizing shovels and trucks. The balance 80 % of oil littorals sedimentations are excessively deep to be mined and are recovered utilizing in situ engineerings, by boring Wellss. Drilling ( in situ ) methods cut down the impact of environmental concerns as they do non necessitate shadowings pools. Advanced engineering is used to shoot steam or other beginnings of heat into the reservoir to heat the deposited bitumen so it can be pumped out to the surface through recovery Wellss. This engineering is called Steam Assisted Gravity Drainage ( SAGD ) and natural gas was used for bring forthing steam. Bitumen production by SAGD is more energy intensive with lower recovery and greater GHG emanations as compared to open cavity excavation. But SAGD requires less H2O and minimum direct land perturbations, having a lower capital cost per M3 of bitumen production. And besides sing the big militias available for bitumen production by in situ engineering, it is of import to happen alternating energy beginning other than natural gas for farther geographic expedition of oil littorals.

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Canada ‘s natural bitumen production from oil littorals has been expected to increase from 1.74 million bpd in 2011 to 5.33 million bpd in 2030, harmonizing to Canadian Association of Petroleum Producers ( CAPP ) forecast study ( 4 ) . The ore from Athabasca oil littorals contains between 8 to 14 % bitumen and remainder is harsh littorals and all right silts and clays which are impregnated with bitumen as shown in figure 1. Compared to conventional rough oil, petroleum bitumen has much lower H to carbon ratio, higher molecular weight, greater specific gravitation, and higher sulfur, N and metal content. Crude bitumen must be upgraded before it can be refined to other crude oil merchandises. OPTI and Nexen integrated the upgrading and SAGD to bring forth to the full upgraded man-made petroleum oil.

Figure 1. Features of oil littorals

Upgrading occurs in two phases, primary upgrading is the initial procedure and achieves most of the value betterment. Secondary upgrading is a refinery procedure that finalizes the quality and stabilizes the merchandise. In an upgrading procedure integrated with SAGD C rejection is the preferable method to increase the H to carbon ratio because the jilted C watercourse can be used as the fuel for SAGD steam coevals. Asphaltenes are formed during the primary upgrading procedure of bitumen as shown in figure 2. The vacuity remainder from the distillment column is sent to the solvent de-asphalting unit where a paraffinic dissolver is used to take the high C content asphaltenes from the vacuity tower undersides. These asphaltenes, about tierce of the vacuity remainder, is liquid at operating temperatures but are really debatable in bitumen upgrading installations ( 5 ) . Asphaltene is extremely aromatic and usually incorporate significant measures of coke precursors, metals, S, and N. Sing the increasing rate of oil sand production in Alberta, managing asphaltenes would be a existent challenge for oil littorals industry. Sing these facts and an option to natural gas for SAGD operation gasification of asphaltenes can be a great option and it increases the serviceability of asphaltene.

Figure 2. Primary upgrading of bitumen ( 5 )

Gasification is a procedure that can change over organic or dodos based carbonous stuffs into gaseous merchandises such as C monoxide, H and C dioxide with a useable warming value utilizing O2/steam/CO2, in an O deficient atmosphere ( 1 ) . This is achieved by responding the fossil stuff with steam at high temperatures ( & gt ; 700A°C ) , at an O deficient atmosphere. So it is a partial oxidization procedure. Complete burning ( oxidization ) of any hydrocarbon fuel outputs CO2 and H2O. However a partial oxidization will ensue in the production of CO and H2. This ensuing gas mixture is called syngas ( from synthesis gas or man-made gas ) or manufacturer gas and is holding calorific value. Gasification is a mature engineering and has been successfully tried since 1800 ‘s over a assortment of feedstocks like wood, biomass, coal, crude oil coke, liquid hydrocarbons, natural gas etc. Presently there are around 120 gasification workss with around 400 gasifiers.

Using gasification engineering the efficiency will be improved and the environmental impacts and nursery gas emanations will be reduced significantly ( 2 ) . Gasification is a dependable option which can bring forth assorted merchandises such as syngas for power coevals, H and redeemable liquid fuels and other valuable merchandises as shown in figure 3. Presents integrated gasification combined rhythm ( IGCC ) is an ideal and suited engineering alternatively of coal-burning procedures which utilize gasification alternatively of burning which leads to higher efficiency and lower environmental impacts.

Figure 1.Gasification-based energy transition options ( 1 )

During gasification the metals in asphaltene get concentrated in gasifier and nowadays in gasifier carbon black. Soot is a general term that refers to impure C atoms ensuing from the uncomplete burning of a hydrocarbon. It is the residuary pyrolyzed fuel atoms that may go airborne during pyrolysis. A survey by Stanford University calculated that C dioxide was the figure one cause of semisynthetic planetary heating, accounting for 48 per centum of the job. Soot was 2nd with 16 per centum of the heating ( 6 ) . The formation of carbon black depends strongly on the fuel composing.

Literature reappraisal

2.1 Types of gasification engineerings

Gasification procedure can be performed in different reactor or gasifier depending on operating status and required state of affairs obligated by fuel belongingss. Three chief groups of gasifier that are available for commercial usage are: fixed bed gasifier, fluidized bed gasifier and entrained-flow gasifier.

2.1.1 Fixed bed gasifier

Figure 4. Fixed bed gasifier ( 8 )

The flow of fuel and the gasification agent in fixed bed is normally antagonistic current. Gass flow upward through a bed of feedstock with the typical atom size of 5-80mm. In this type of gasifier, the abode clip is comparatively long in scope of 0.5-1 hr which is suited for big atoms. This sort does n’t hold the temperature restriction of fluidized bed, so they can run at low temperature and bring forth merely dry ash or operate at high temperature as a slagging gasifier. In order to keep permeableness of the fixed bed in slagging fixed bed, physical strength and cocking behaviour of coal atoms are really of import factors. They are chiefly used for the production of heat and besides for little scale power coevals ( 2 ) .

2.1.2 Fluidized bed gasifier

Figure 5. Fluidized bed gasifier ( 8 )

In fluidized bed gasifier feedstock fuel atoms normally with size of 0.5-5mm are suspended in a bed of coal ash, sand and other stuff and the bed is fluidized by gas flow. This sort of gasifiers operates at low temperature in the scope of 600-1000A°C and the feedstock should be dry and crushed. Ash agglomeration in fluidized bed causes uneven bed fluidization so in order to avoid this affair the ash merger temperature of fuel should be higher than operating temperature. They by and large operate in the MWh scope, and are by and large of two types, i.e. bubbling fluidised bed ( BFB ) gasifiers and go arounding fluidised bed ( CFB ) gasifiers ( 2 ) .

2.1.3 Entrained flow gasifier

Fuel atoms and gases flow at the same time from top to bottom in entrained-flow gasifier. Therefore due to this sort of flow constellation the abode clip of fuel atoms is really short in the gasification zone ( normally in the scope of 5-10s ) . Consequently due to this short abode clip in entrained-flow gasifier in order to hold high C transition, the fuel should be pulverized and the system should be designed to run at high temperatures. Due to intense reaction status inside of this sort of gasifiers, entrained-flow gasifiers are capable of working with high throughput and can utilize a broad scope of less reactive coals. Entrained-flow gasifier are besides capable of working with dry or slurry provender depending on their design nevertheless dry-fed gasifier is more coal efficient and less O consuming in comparing with slurry-fed, because slurry-fed system requires extra energy to vaporize H2O in slurry. These are by and large larger units for power coevals and operate at really high temperatures, in surplus of 1200 C and for really short abode times. They are usually fired with fossil fuels ( 2 ) .

Generic features of entrained flow gasifiers include:

aˆ? High-temperature slagging operation ;

aˆ? Entrainment of some liquefied scoria in the natural syngas ;

aˆ? Relatively big oxidant demands ;

aˆ? Large sum of reasonable heat in the natural syngas ; and

aˆ? Ability to vaporize all coal regardless of rank, coating features or sum of mulcts.

Many IGCC workss use entrained bed gasifiers. Entrained bed gasifiers are available in much larger capacities ( 100 MWe ) than other types, but these are more normally used for fossil fuels like coal, refinery wastes, etc.

Figure 6. Entrained flow gasifier ( 8 )

2.2 Gasification theory

Gasification can be summarized into two major stairss ( 2 ) :

– Pyrolysis ( besides called thermolysis ) : during pyrolysis organic substances are decomposed into solid residue ( i.e. char ) and volatiles when it is heated up in the absence of O.

Organic affair + heat char + liquids + gases

– Gasification The reaction between the char ( from pyrolysis ) and vaporizing agents including O, CO2 or steam.

Char + vaporizing agent + heat gases + ash

Furthermore, gasification reactions can be summarized into these parallel reactions:

Partial Oxidation and complete burning with

( a?†H = -405.9 kJ/mol )

( a?†H = -123.1 kJ/mol )

Partial oxidization and complete burning with O are exothermal reactions which provide required heat for continuing gasification reactions by utilizing much of the O in the gasifier.

Chemical reaction of CO2 with C ( Boudouard ‘s reaction )

( a?†H = +159.7 kJ/mol )

The reaction is endothermal and returns really easy at temperatures below 1000 K and is inhibited by its merchandise.

Water gas reaction

( a?†H = +118.9 kJ/mol )

This endothermal reaction is favoured by elevated temperature and decreased force per unit area, and in the absence of accelerator, occurs easy at temperatures below 1200 K.

Hydrogasification reaction

( a?†H = -87.4 kJ/mol )

Because of some thermodynamic and kinetic restrictions hydrogasification reaction is ever uncomplete and it produces some char residues ( 2 )

The following gas stage reactions are of import for the concluding gas quality to act upon H2/CO ratio. This ratio is of import if the gas is for synthesis or H production.

Water gas displacement reaction

( a?†H = -40.9 kJ/mol )

Steam methane reforming reaction

Methanation reaction

( a?†H = -206.3 kJ/mol )

Methanation reaction is really slow except at high force per unit area and increases the thermal value of the gas ( 2 ) .

Asphaltenes

The name “ asphaltene ” was foremost used by J.B. Boussingault in 1837 when he observed that the distillment residue of petroleum oils had asphalt-like belongingss. Asphaltenes are indissoluble in n- pentane ( or n-heptane ) and are soluble in methylbenzene. Asphaltenes are the heaviest and most polar molecular constituent of any carbonous stuff such as rough oil, bitumen or coal. Asphaltenes consist of C, H, N, O, and S and hint sums of V and Ni. The Hydrogen: C ratio is about 1:1.10 to 1.20, depending upon the asphaltene beginning and the dissolver used for extraction.

Asphaltenes have been the topic of considerable treatment and contention in the literature. Controversy and ambiguity arise mostly because of the deficiency of chemical definition of asphaltene mixtures for which composing is dependent upon the beginning stuff and method of isolation. Asphaltenes are by and large classified by the peculiar paraffin used to precipitate them from the benzene-soluble part of the provender. Therefore, there are pentane asphaltenes, hexane asphaltenes, heptane asphaltenes, and so on. However, the present inclination is to specify the stuff precipitated by n-heptane as asphaltenes. The inter-relationship of mutual opposition and molecular weight in footings of solubility behaviour can be better understood and it becomes clear that there is non a specific chemical composing or a specific molecular weight description for asphaltenes. Rather, asphaltenes contain a broad distribution of mutual oppositions and molecular weights.

Insoluble

Petroleum Residuum

Benzene

Dainty

Soluble

Pentane

Dainty

Soluble

Deasphaltened Oil

Insoluble

Asphaltenes

Figure 7. Separation of asphaltenes from crude oil remainder

The authoritative definition of asphaltenes is based on the solution belongingss of crude oil remainder in assorted dissolvers. The asphaltene fraction of crude oil petroleum is defined harmonizing to Nellensteyn ( 9 ) as the fraction indissoluble in low boiling point paraffin hydrocarbons but soluble in C tetrachloride and benzine. Harmonizing to Pfeiffer ( 10 ) , asphaltene is defined as the fraction indissoluble in n-heptane but soluble in methylbenzene.

The asphaltenes from different beginnings have specific belongingss. Table 1 shows the belongingss of asphaltenes from Fosterton and Neilburg in Saskatchewan and Athabasca in Alberta, Canada, San Fernando in Columbia and Orimulsion in Venezuela. Asphaltenes by and large contain really low ash ( largely less than one per centum ) , but are high in volatile affair and fixed C. The sulfur content of the asphaltenes varies based on the beginning of asphaltenes. The H/C ratio is around one due to it is being composed of largely aromatic constituents. The feedstock for this survey is chiefly asphaltene from the Athabasca basin.

Fosterton

( 13 )

Neilburg ( 13 )

San Fernando

( 14 )

Orimulsion

( 15 )

Athabasca

Proximate Analysis ( wt. % )

Volatile affair

23.9

61.5

78.89

58.18

61.72

Fixed Carbon

75.1

38.1

19.89

12.84

37.88

Ash

0.88

0.39

0.53

0.18

0.40

Ultimate Analysis

C

55.4

82.6

81.1

84.28

80.3

Hydrogen

5.2

7.8

8.62

10.33

8.0

Nitrogen

0.5

1.1

1.01

0.64

1.2

Second

1.7

6.5

4.29

3.95

8.2

Oxygen

37.2

2

4.39

0.55

2.5

H/C

1.1

1.1

1.3

1.5

1.2

Table 1. Typical belongingss of asphaltenes from assorted beginnings ( 12 )

2.4 Asphaltene/Heavy oil gasification

Watanabe et Al ( 16 ) developed a numerical theoretical account for the design and public presentation rating of the excess heavy oil gasification in an entrained freshness gasifier. Four reaction procedures like atomisation, pyrolysis, coke gasification and gaseous stage reaction were modeled. Heterogeneous stage reaction construct of this theoretical account is shown in figure 8. The atom conveyance is modeled with Lagrangian atom tracking attack. Comparison between the computational consequences and the experimental consequences on “ Research Gasifier for Liquid Fuel ” of CRIEPI shows that the consequences such as temperature distribution, the gas composing distribution, the warming value and the C transition efficiency are lucifers good. Vaezi et Al ( 17 ) besides developed a numerical theoretical account for gasification of the same provender based on the experimental consequences of Ashizawa et Al ( 15 ) . This survey did non see heterogenous char reactions.

Figure 8. Heterogeneous stage reaction theoretical account

Ashizawa et Al. ( 15 ) investigated the gasification features of excess heavy oil in a research-scale gasifier with a capacity of 2.4 ton/day. The feedstock for this survey was Orimulsion, which is a bitumen-based fuel constituted by 70 % bitumen and 30 % H2O. The set up consisted of a pressurized ( 1.9 MPa ) entrained flow type gasifier, a raw-gas ice chest and, 15m3 feedstock storage armored combat vehicle along with a supply system. The gasifying agent used was O with an O ratio of 0.37 to 0.41. They found that increasing the O ratio leads to increase of C transition while it reduces the cold gas efficiency ( CGE ) and thermal value of merchandises. The HHV moisture values were in the scope of 9.5-10.5 MJ/m3 and CGE was about 75-80 % and C transition was more than 97 % . They collected char and gas samples at different degrees of the gasifier and found that high C transition efficiency was obtained at top 1/3 of the reactor. Besides, gas analyses revealed that CH4, H2O and CO concentrations decreased along the gasifier while H2 and CO2 concentrations increased.

Moreno et Al. ( 14 ) investigated gasification of Colombian asphaltenes from San Fernando petroleum oil with O in a research lab graduated table batch procedure. The aim of their work was to happen the consequence of temperature and gasifying agent flow rate on syngas composing. The asphaltenes sample ( 15 gr ) was placed in a horizontal cannular oven and heated up to 1000 A°C. The uninterrupted flow of O2 diluted with Ar at 170 pounds per square inch ( 11.6 standard pressure ) was supplied as the gasifying agent. The temperature of the gasification experiments were varied in the scope of 900 to 1000 A°C. They consequences indicated that increasing the temperature improved the syngas composing ( i.e. , CO and H2 content ) and C transition since gasification at higher temperatures decreases the sum of pitch and other byproducts. They varied the vaporizing agent from 33 % to 47 % ( of the sum of O required for complete burning ) and it was established that the best consequences in footings of CO and H2 content is obtained at 40 % of vaporizing agent.

Nassar et Al ( 18 ) studied the application of nanotechnology for gasification/cracking of asphaltene. The surface assimilation and gasification of asphaltenes were investigated utilizing thermohydrometric analysis in the presence and absence of different metal oxide nanoparticles. They found that the activation energy and oxidization temperature of asphaltenes decreased significantly in the presence of nanoparticles.

Soot formation

Soot is a carbonous solid stuff with 10 mole % H formed during pyrolysis and fire burning. Soot is normally formed when the procedure conditions are sufficiently fuel rich to let condensation or polymerisation reactions of the fuel ( and its initial decomposition merchandises ) to vie with oxidization ( 19 ) . Harmonizing to Neves et Al ( 20 ) polycyclic aromatic hydrocarbons ( PAH ) are merchandises of primary pyrolysis and the pre pointers of the carbon black atoms in a secondary pyrolysis procedure. Soot exists in the signifier of both single atoms and agglomerate comprised of several primary atoms. The cardinal unit of carbon black agglomerates are the spherules ( 21 ) . Spherule diameter varies from 10-50 nanometer. The figure 9 shows the form of carbon black atom dwelling of bunchs ( 4000 spherules ) or ironss of spherules. Soot in burning fires is really of import because it significantly heighten the radiative heat transportation with its big surface country. The near-burner fire temperature could be lowered several hundred grades due to the excess heat transportation to the environing walls due to the presence carbon black atoms in add-on to gas, char and ash. The low temperature at the burner will diminish the thermic NOx every bit good as fuel NOx formation.

Soot contributes to many serious jobs in the industry. In add-on to lending to pollution, carbon black enhances the emanation of other pollutants from fires ( e.g. , C monoxide ) . Soot has been suggested to be a major subscriber to planetary heating: its consequence in raising the planetary surface air temperature is dual to that of C dioxide ( 22 ) . Besides, smaller carbon black atoms are suspected to exhibit unsafe effects on human wellness as they penetrate easy into the respiratory piece of lands. Soot formation besides affects the efficiency and care of burning device.

Figure 9. Micrograph of Diesel carbon black ( 21 )

Soot formation has been extensively studied in different experimental devices such as fires, daze moving ridge reactors, flow reactors, utilizing different hydrocarbon fuels. Chen ( 23 ) performed coal pyrolysis experiments in an inductively-heated beaming drop-tube furnace in an inert Ar atmosphere. He found that the outputs of tar/oils plus carbon black in the secondary pyrolysis experiments were changeless and were equal to the tar-plus-oil outputs obtained at the longest abode clip in primary pyrolysis experiments. For a high-volatile bituminous coal at higher temperatures, more than 25 % of the coal mass ( daf ) was converted to soot. The high carbon black outputs reported by Nenniger, et Al. ( 24 ) , Wornat, et Al. ( 25 ) and Chen ( 23 ) were likely due to the inert conditions, since no devastation occurred by oxygen-containing species. The profiles of soot output versus temperature in these coal pyrolysis experiments were non bell-shaped ; the soot outputs increased with temperature monotonically. Table 2 summarizes their experimental consequences.

Frenklach et Al ( 27 ) modeled the carbon black atom nucleation and growing in laminar premixed hydrocarbon fires. The simulation of soot atom formation included fuel pyrolysis, polycyclic aromatic hydrocarbon formation and its planar growing, curdling into spherical atoms and besides the surface growing and oxidization of atoms. Shurupov ( 28 ) concluded that the pyrolysis temperature, reactant abode clip and the feeding concentration of the fuel are the chief parametric quantities that govern soot formation during pyrolysis of any fuel. The initiation periods of nucleation of the carbon black atoms for different hydrocarbons may be different.

Soot formation is approximated by four phases as follows ( 29, 30 ) :

Nucleation of soot atom ( origin and growing of PAHs )

Particle curdling

Particle surface reactions ( Growth and come up oxidization )

Particle agglomeration

( 23 )

( 25 )

( 24 )

Table 2. A sum-up of coal pyrolysis experiments conducted by three research workers. ( 26 )

The presumed tracts for soot formation from coal given by Chen et Al ( 31 ) are shown in figure 10. They studied the gasification of coal biomass blend in an atmospheric fluidized bed. Their consequences showed lessening in concentration of carbon black along with the addition on O/C ratio.

Figure 10. The presumed tracts for carbon black formation ( 31 )

The Long Lake installation, operated by NEXEN, is the first large-scale integrating of oil-sands Steam Assisted Gravity Drainage and Upgrader with gasification ( 32 ) . Asphaltene from the Upgrader OrCrude procedure is used as the feedstock, holding viscousness of 300 Central Time at 300A°C. The gasification of the feedstock occurs by partial oxidization utilizing pure O. A little sum of C, along with all the non-hydrocarbon constituents in the provender, exits the gasifier as particulates with the syngas. These soot atoms create erosion/corrosion issues at the downstream of the gasifier as the syngas is cooled down. The available literature gives small information about the features of the carbon black formed during asphaltene gasification. So it is selected as the chief aim for the current survey. The consequences will assist in rectifying the industrial jobs related to eroding of tubing walls in the downstream of the gasifier.

2.6 Important Findingss from Literature

Entrained flow gasification is a proved engineering normally used for fossil fuels like coal and refinery wastes. Many entrained bed gasifiers are in operation at larger capacities than other types.

Asphaltene gasification experiment is conducted in a research lab graduated table batch procedure in which the temperature is varied from 900 to 1000oC. It is much below the normal operating temperature of entrained bed gasifiers ( & gt ; 1300oC ) .

Gasification of excess heavy oil revealed that an addition in O ratio will take to increase in C transition but reduces the cold gas efficiency and calorific value of merchandises.

A lessening in concentration of carbon black is observed with the addition in O/C ratio during the atmospheric fluidized bed gasification of coal biomass blend.

When the temperature of the coal pyrolysis experiment is varied between 1130 to 2200oK, the pitch output decreases with temperature and soot output additions with temperature.

Small information is available about the features of carbon black during asphaltene gasification.

Aims

The chief aim of this survey is to develop cardinal apprehension of the formation of soot atoms during asphaltene pyrolysis and gasification in an entrained flow gasifier. The output and belongingss of carbon black formed in inert ambiance ( pyrolysis ) may be different from that formed in the presence of oxygen-containing species ( gasification ) . An electrically heated bead tubing furnace will be used for the gasification experiments. The chief aims are:

Find the consequence of pyrolysis temperature on the soot output by changing the temperature from 1200 to 1400oC with an interval of 50oC.

Find the optimal scope of operating conditions of the gasifier with regard to the generated syngas and mineral sedimentations by changing the conditions near to the existent industrial gasifier. The temperature will be varied from 1200 to 1400oC.

Analyze the carbon black formed during both gasification and pyrolysis in item sing the atom size distribution, chemical composing, construction, morphology etc.

Find the consequence of syngas chilling temperature on the interaction of soot minerals and the mechanisms of mineral evaporation/re-condensation and sedimentation formation. The gasifier issue gas can be subjected to command chilling and soot aggregation can be done at specified temperatures. The soot aggregation temperature will be varied from 50 to 300 oC.

Investigate the function of soot atoms on the erosion/corrosion of tubings in the downstream of gasifier.

Estimate responsiveness of asphaltene char with regard to the of import gasification reactions utilizing thermohydrometric analyzer ( TGA ) .

CFD simulation of asphaltene gasification in an entrained flow gasifier utilizing the kinetic informations developed with TGA.

Methodology

4.1 Experiments in an Entrained flow gasifier

In an entrained flow gasifier, an atomized liquid fuel/ pulverized solid fuel is gasified with oxygen/air and/or steam in co-current flow. The chief features of this type of gasifier are the high operating temperatures and high warming rates and short abode times which in bend consequence in high throughput of fuels compared to other conventional gasifiers such as fluidized bed and fixed bed. Knowing thermic behavior of the fuel is a preliminary phase to analyze assorted procedures such as fuel gasification or fuel burning. Char oxidization is the rate-limiting measure and determines the C transition and the ash formation.

The experimental apparatus of the bead tubing furnace ( DTF ) is shown schematically in Figure 11 ( 12 ) . The reactor furnace consists of an electrically het perpendicular nucleus of Mullite tubing ( 2.5 ” ID, 60.875 ” tallness ) . The temperature of the reactor is fixed along the tubing length utilizing three PID temperature accountants in three different zones. A provender nose in combination with a primary flow of N2 is used to entrain and feed the fluid particles into the reactor. For gasification Air and N2 are preheated on the preheating subdivision of tubing before responding with samples. Pyrolysis merchandises are collected through a water-cooled aggregation investigation.

To forestall condensation of gaseous merchandises on the inner shell of the aggregator investigation, the investigation is equipped with a sintered chromium steel steel inner shell through which gas ( N2 ) is passed. Following the aggregation investigation, the cooled watercourse is passed through a cyclone where char and ash samples are separated from fluke gas and collected. Then, the fluke gas is passed through a bag filter to pin down sub-micron atoms and a capacitor to take out the staying H2O vapour. The force per unit area in the gasifier is fixed in propinquity of ambient via a vacuity pump.

The bead tubing furnace will be used for the pyrolysis every bit good as gasification of asphaltene liquid. The carbon black atoms will be collected in both the instances utilizing a cascade impactor for farther word picture. The cascade impactor is capable of roll uping literally all the atoms with regard to their atom size at different phases. The char atoms of heavier size can be collected in the cyclone centrifuge which is connected prior to the cascade impactor. This char prepared at different temperatures will be used for the responsiveness surveies utilizing thermo hydrometric analyzer. The kinetic informations therefore obtained will be used for the computational fluid kineticss ( CFD ) simulation of the asphaltene gasification. The consequence carbon black belongingss formed in presence of O incorporating species ( gasification experiment ) will be examined by qualifying the gasification carbon black. The vaporization and re-condensation of the soot minerals can be studied by commanding the temperature of the aggregation investigation and tubings linking to cascade impactor. The syngas quality during the gasification experiment can be monitored utilizing the micro-GC connected to the system. Thus the fluctuation of syngas belongingss can be estimated at different runing conditions.

Figure 11. Conventional diagram of entrained flow gasification system

4.2 Word picture of the resulting samples

4.2.1 Surface country

Char surface country can be measured by volumetric surface assimilation analyzers and BET method. Entire surface country of char will be measured utilizing two techniques: N2 surface assimilation and CO2 surface assimilation. These two techniques are different in surface assimilation temperatures and the used gases. In the first technique, N2 is adsorbed at 77K and the isotherm will be interpreted farther by BET equation. In this technique, the surface country of meso and macropores ( greater than 20 A ) will be measured while the surface country of micropores will be found by CO2 surface assimilation at 0A°C ( 32, 33 ) .

4.2.2 Microscopy

Scaning Electron Microscope ( SEM ) can be used to detect the morphological construction of char and to see how a coal atom is affected by different procedure conditions ( 32 ) .

4.2.3 Proximate and ultimate analyses

Proximate and ultimate analysis will be carried out based on ASTM D 3172-89 criterion. Besides, it could be used to happen the per centum of the minerals. These methods will be done harmonizing to the processs reported in the literature.

4.2.4 Char denseness

Relative majority packing denseness will be measured as the char denseness. This is an index of the nature of char and provides some apprehensions about the reaction of char with gases like CO2, O2 and H2O ( 32 ) .

4.2.5 Particle size distribution ( PSD )

Char and coal atom size distributions will be found by Malvern laser-scattering. In order to forestall char atoms amendss, foremost they will be dispersed in propyl alcohol and undergo a mild supersonic scattering before analysing for PSD.