mini project

2014

Group Members

Mehrran Rasheed Goraya 10043123-029

Hafiz Salman Farooq 10043123-024

Tanveer Ahmed 10043123-031

Humza Iqbal 10043123-033

Project Supervisor

Engr. Muhammad Shahbaz

Chemical Engineering Department

University of Gujrat

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Contents1-Abstract …………………………………………………………………………………………………………………………………………….. 2

2-Introduction [ l ]:-....................................................................................................................................1

3-Process selection.................................................................................................................................1

4-Equipment selection...........................................................................................................................1

5-Mass balance on gasifier...................................................................................................................1

6-Design of the Circulating Fluidized Bed Reactor .........................................................................1

7-Fluidization...........................................................................................................................................1

8-Design of the Fluidized bed..............................................................................................................1

9-Conclusion:-..........................................................................................................................................1

10-References:-.......................................................................................................................................1

Group # 1 Chemical 7th Date 15/01/2013

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1-Abstract Gasification of different fuels got attention in Pakistan due to fluctuation in natural gas supply. The production of synthetic natural gas, hydrogen production for ammonia synthesis from natural gas also affected. To maintain the production of these gases, there are different ways like pyrolysis, combustion, or gasification of Coal, biomass or wood. These methods are carried out in different reactors like fluidized bed, entrained bed and fixed bed reactor in which there are different medium such as by introducing the steam, air or oxygen. In this paper, we are going to gasify the wood by introducing the steam in the presence of Nickel-Olivine catalyst. We study the different types of reactor and will design the circulating fluidized bed which is, after making comparison of number of reactors, in the range of our desired capacity (20MW-100MW) at the temperature 9000 C and pressure 1 Bar for low heating value of wood rather than higher heating value and 90% of conversion. The main objective is the design of fluidized bed at superficial velocity and study of porosity and sphericity of wood and Nickel-Olivine catalyst.

2-Introduction[l]:-Gasification is actually a chemical process in which conversion of carbonaceous materials into chemical feed stock or gaseous fuel. Carbonaceous fuel may be any biomass. Basically gasification is a process in which partial combustion of biomass yields the production of carbon monoxide, hydrogen and traces of methane which are combustible gases. . This mixture is called producer gas or syn gas or synthetic gas. The purpose of gasification in not just conversion, production of chemicals is also have main importance of gasification. In fact the first application of gasification was to produce charcoal for iron ore reduction and not for gaseous fuel in 4000 B.C.E.

On the other hand the producer gas which is produced can be used in number of processes like,

1. Substitute for furnace oil2. Run internal combustion engines3. Chemical feedstock for industries4. In producing synthetic petroleum via the Fischer–Tropsch process5. Used for the production of synthetic natural gas (SNG), ammonia and methanol

One also main application of gasification is that there is a problem of using solid fuel, like wood which is used in boiler, to produce heat by combustion but this equipment is very expensive and very low energy recovery. Hence it is very essential to convert wood into gaseous fuel by gasification. . Hence it is also a big application of gasification.


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2.1-Historical Background [m] :-

First gasification process is investigated by Thomas Shirley. , who in 1659 experimented with “carbureted hydrogen” which was the previous name of methane. Then with the passage of gasification milestones different experiments and discoveries were made.

1788 1801 1861 1926

1997 2001

In Pakistan energy crisis is very severe. In every year energy demand is increasing by 8%. From recent last twelve years, and this trend is continuous. Our 50% yearly export earning has been consumed in oil import bill. Federal minister of information Senator Pervez Rasheed said.

Small and medium enterprises (SMEs) and also other industries could use wood gasification to generate their own electricity and this would help them to avoid the negative impact of the power crisis,


AdvancedGasification &Renewable energyProjects

First commercialGasification plant in United States

Robert Gardner: First gasification patent

Fourcroy: Water gas shift reaction

Siemens gasifier:First successful unit

Winkler: Fluidized bedGasifier

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3-Process selection3.1-Selection of fuel:-

Biomass fuel is more close to the hydrogen corner and oxygen. It means, in biomass there is more hydrogen and oxygen as compared to coal.

Lignin have much low oxygen and high carbon contents.

Peat is in the direction towards the carbon corner, which means it is like a high-carbon biomass.

Coal resides further towards the carbon corner and lies close to the oxygen, which means that coal having low oxygen and more rich in carbon contents.

Anthracite resides further towards the carbon corner because it has more carbon contents.

Carbonization shows that the product towards the carbon through the production of solid char; fast pyrolysis takes it towards hydrogen corner and away from oxygen corner, which means high liquid product.

Gasification by using oxygen takes the gas product towards the oxygen corner.

Gasification by steam takes the process away from the carbon corner.

Here we want to produce syngas (CO+h2) so we need biomass for the production and naturel sources like crude oil, coal and natural going to be end.

Biomass like municipal solids waste, cow dung for the production of methane are needs to be utilized for replacement of natural fuels.

In Pakistan there is much necessary to install the technology for the production of biogas, biodiesel and bioethanol for the decomposition of biomass and also for the replacement of natural fuels.

3.2-Biomass conversion:-

There are two different routes of the conversion of bio mass


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3.2.1-Biochemical route

1) Digestion Anaerobic Aerobic

2) Fermentation

3.2.1.1-Digestion:-

The major constituents of anaerobic digestion obtained are methane and carbon dioxide.

Aerobic digestion, is a biochemical breakage of biomass, the reaction occur in the presence of oxygen. It takes the excess oxygen from the air, produces carbon dioxide, heat, and a solid digestate.

3.2.1.2-Fermentation:-

In fermentation, some biomass is converted into sugars using acid or enzymes. This sugar can be converted into ethanol or other chemicals with the help of yeasts. In this process, liquid product is obtained.

3.2.2-Thermochemical route

There are four different processes for the thermochemical conversion of biomass which are

Pyrolysis Gasification

o Supercritical Water

o Oxygen

o Steam

Combustion Liquefaction


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3.2.1-Combustion:-

Combustion is basically the oldest utilization of biomass, which means that Civilization starts when fire is discovered. From burning of forest wood humans learned that how to cook and how to be warm. Combustion is an exothermic reaction due to oxygen and the hydrocarbons. This Reaction releases the heat which is presently the largest source for energy consumption, which is more than 90% of the energy from biomass.

3.2.2Pyrolysis:-

Pyrolysis takes place when there is no oxygen present, except in cases where partial combustion is allowed to provide the thermal energy needed for this process. Pyrolysis is basically a thermal decomposition of the biomass into gas, liquid, and solid.

It’s been three types:

Slow pyrolysis Torrefaction, or mild pyrolysis Fast pyrolysis

3.2.3-Gasification:-

Fossil or non-fossil fuels (solid, liquid, or gaseous) can be converted into useful gases and chemicals after gasification. It needs a medium for conversion, which can be gas or supercritical water. Gaseous mediums include air, oxygen, subcritical steam, or a mixture of these.


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There are three major reasons for such a transformation:

For the increase of heating value of the fuel by rejecting components like nitrogen and water.

For removal of sulfur and nitrogen when burnt the gasified fuel does not release them into the atmosphere.

For the reduction of the carbon-to-hydrogen (C/H) mass ratio in the fuel.

3.2.4-Liquefication:-

Solid biomass can be liquefied into liquid fuel through pyrolysis, gasification as well as by hydrothermal process. In hydrothermal process, biomass is converted into an oily liquid when biomass is reacted with water at the temperature of (300-350) and at high pressure of (12-20MPa) for a period of time.


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4-Equipment selection4.1-Gasifiers:-

A reactor in which the reactions of gasification occur is called as gasifier. Gasifier/Equipments for the purpose of gasification exist in many forms, which are dependent upon the type and size of feed, operating pressure and temperature and the medium which is being used for gasification. Following are the technological options for Gasifiers that can be applied for the gasification purpose: - [5] [19]

A. Fixed(Moving) bed Gasifiersi. Updraft/ Countercurrent

ii. Downdraft/ Co-current iii. Cross draft

B. Fluidized bed GasifiersC. Entrained flow GasifiersD. Allothermal GasifierE. Supercritical Gasifier

4.1.1-Fixed Bed Gasifier [18] :-

The feed and the gasifying medium i.e. hot air or steam is entered into the gasifier from two different openings thus forming three types:

4.1.1.1-Updraft/Countercurrent Gasifier [6]:-

In this type, the feed i.e. biomass, is introduced from top side opening and the medium of gasifying i.e. hot air or steam is entered from the lower side opening of the gasifier.[3][4] As the entering feeds are preheated by the outgoing hot SNG and hot ash, the efficiency is relatively high and the leaving temperature is lower. 1-2 hours residence time is required for this type of the gasifier.

4.1.1.2-Downdraft/Co-current Gasifier [6]:-

When the feed and the steam are entered in the gasifier from the same side and move in the same direction, the gasifier is known as co-current gasifier. Here the ash produced is also burned (cracked) as the SNG is being passing through the combustion zone.


Gas

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4.1.1.3-Cross draft Gasifier:-

Feed is entered from the top side while the gasifying medium is introduced from any other side other than lower and upper side. In this type the height of the gasifier is much reduced, While pressure drop is high than others.

Mixing and heat transfer are poor in all these three types of gasifiers so that fuel, temperature and gas mixtures are not uniformly mixed. Agglomeration of fuel is also a drawback in these gasifiers.

4.1.2Fluidized Bed Gasifiers [6] [9] [18] :-

This is the type in which the feed is fluidized by the help of gasifying medium. During the operation, the steam jet is injected which pushes up the biomass i.e. suspending the feed. A clean gas which is then nitrogen free is obtained. They are also known as CFBG (Circulating Fluidized Bed Gasifier) /FICBG (Fast Internally Circulating Fluidized Bed). [14][15] Velocity range for these gasifiers is 3-10m/s.

When velocity is lower than this range but still high, then the bubbling fluidized bed is formed instead of the circulating fluidized bed.[11][12]

4.1.3-Entrained flow Gasifier [6] [18] :-

These gasifiers are operated at relatively high temperatures and deal with small size particles close to 0.1 mm. Since particles are in small sizes and they are burned quickly hence residence time is lower for these gasifiers. Instant burning of small particles causes the formation of SNG and the methane is not produced in these gasifiers.

4.1.4-Allothermal Gasifiers:-


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Twin bed gasifier is a simple example of this type. When feed is not heated directly i.e. heat is provided either by another medium or by heating of the walls of the gasifier, then the indirect gasification occurs which is also known as the Allothermal gasification. Heat loss is greater in this type due to which thermal efficiency is also lower.

4.1.5-Supercritical Gasifier:-

When moisture contents are higher in the feed then super critical gasification is employed which is the result of supercritical properties of the water at extreme high pressure and temperature. Pressure may range between 30 MPa to 50 MPa and temperature may be up to 500 C. in this process, since water i.e. steam is being used in greater quantity so the resultant SNG gas contains Carbon Dioxide in large amount and methane and Carbon Monoxide are less in amount.

4.2-Selection of Gasifier for Gasification of wood:-

Gasifiers are selected for their job

according to the size of the feed. Entrained flow gasifier is used for very low size feed. Similarly fluidized bed reactor is used for larger size particles with range from 3-10 mm size. Moreover, temperature range for former is 1200-1500 C and for latter is 750-900 C. A graphical relationship between different types of beds and their capacity is shown here. [19]

Since we are taking wood as feed and the capacity that we have selected is 100MW so according to above figure we have equal opportunity to select fluidized bed and entrained flow gasifier. Efficiencies based on LHV are 54%, 58% and 67% for entrained flow, CFB and Allothermal gasifiers respectively. [1]

Fluidized bed is important because of its well mixing and uniformity in temperature. [16]

This temperature uniformity is the property which don`t permit the fuel to agglomerate. Operating temperatures for the entrained flow gasifiers are relatively high and also they require very small size feed and our feed size comes in the range of the fluidized bed. Hence fluidized bed is chosen for this project.

Fluidized bed depending on the velocity of the entering fuel, can be a bubbling fluidized and circulating fluidized bed gasifier. [12] Lower velocity causes fluidization but only bubbles are formed but within the range of 3-10m/s velocity, the circulation is involved i.e. circulating fluidized bed. Hence Fast Internally Circulating Fluidized Bed is chosen for this project.


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5-Mass balance on gasifierCapacity 100 MW

Low eating value of wood can be calculated by this formula

5.1-Low heating value:-

LHV=HHV-Hg {9(fraction of hydrogen)-(fraction of moisture contents)} [a]

5.2-Composition of elements:-

Ultimate Analysis (Dry Basis) of Some Biomass [b]

Fuel Percentages

Carbon 50.6

Hydrogen 6.0

Oxygen 0.3

Nitrogen 0

Sulfur 41.7

Ash 1.4

High heating value 19958kj/kg

5.3-Basic assumptions:-


Parameters values

HHV 19958KJ/kg

Hg(latent heat of steam) 2260kj/kg

H(fraction of hydrogen) 0.06

M(fraction of moisture contents)

0.015

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LHV= lower heating value of wood

Fraction of hydrogen in wood =6%

Moisture contents = 15%

So, we get

For 100 MW

We know that

1MW=106 j

And for 100MW

100x106 joule

Base; 1kg

Steam=3.8605kg

Ash=0.077kg

Lower heating value is 17991x103 for = 1kg

For 1x108 j feed is required = (1/17991x103) x1x108

Which is


LHV=17991kj/kg

Reactor Feed=5.515kg Syngas =4.9635kg

Feed of wood=5.515 kg

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Steam required for 1 kg of wood for gasification = 0.7 kg [c]

Steam required for 5.515 kg of wood for gasification = 0.7 x 5.515

1 kg of produced 0.662 kg of syngas[d] which that syngas production =0.662 x 5.515

5.4-Average density of syngas:-

Average density=0.95kg/m3

5.5-Volumetric flow rate:-

V=mas flow rate/average density

=3.651/0.46

=7.937m3/s

Mass of CO gas = % volume (density) (volumetric flow rate)

= (0.257) (0.507) (7.937)

= 1.034 Kg/Sec


=3.8605 kg of steam

=3.651 kg of syngas

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5.6-Calculated composition of gases in product gas:-

5.7-Ash contents:-

Ash contents= (%age fraction of ash) (total mass of feed)

= (1.4/100) x (5.515)


=0.0772 kg of ash

Component

s

%

Volume Density Mass(Kg/sec)

CO 25.67 0.5071 1.034

CO2 21.66 0.7967 1.3697

H2 20.69 0.0365 0.0599

CH4 5.16 0.2904 0.1189

C2H4 1.41 0.5431 0.0608

C2H6 0.04 0.5444 0.0017

N2 0.15 0.5072 0.006

H2O 25.16 0.3261 0.6512

H2S 0.06 0.6155 0.0029

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6-Design of the Circulating Fluidized Bed Reactor

6.1-Methodology:-

In order to design the circulating fluidized bed reactor, the design of the fluidized bed is of the main important. But for the design of fluidized bed, the physical properties of Catalyst such as nickel olivine and fuel (fine particles of wood) should be known. First of all internal diameter of the reactor is known in order to initiate the design of fluidized bed.

6.2-Design parameters:-

The typical design parameters are

Solid Volume Product Gas Volume Gasifier Volume Gasifier Diameter Wall thickness Residence time

6.3-Calculation Procedure:-

For the design considerations the whole reaction occurring in the Gasification process should be keep in mind

6.4-Main Reaction [e] :- Three main reactions of the process are following:

C+O2 CO2

C+1/2 O2 CO

C+ H2O CO+ H2

6.5-Other Reactions in Gasifier [e] :- C+ CO2 2CO

H2O + CO H2+ CO2

CO + 3H2 CH4+ H2 O


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N2 +3H2 2NH3

a) C+CO2 2CO + 164.9 kJ/Kmolb) C+H2O CO+H2 + 122.6 kJ/Kmol

Equations (a) and (b), which are the main reactions of reduction, shows that reduction requires heat. Therefore the gas temperature will decrease during reduction.

6.6-Considerations:-

Low heating value (LHV) of wood = 17991.8 KJ/Kg

Flow rate of wood feed = 5.5158 Kg/s

Temperature of Gasifier = T = 8500 C = 1123 K

Pressure of Gasifier = P = 1 bar = 101.325 pa = 1 atm

Consider the behavior of Circulating Fluidized Bed Reactor as Plug Flow Reactor

There are three main reactions

C+O2 CO2

C+1/2 O2 CO

C+ H2O CO+ H2

Among these reaction (3) is slowest step according to thermodynamic study of these reactions.

Hence considering the reaction 3, kinetics study shows that it is a 2nd order reaction so

Now

6.7-Performance Equation of Plug flow reactor [f] :-

This equation is basically the relation between time, concentration, conversion and flow rate

t=C c 0∫0

X cf dX c

−rc

=−∫Cc0

Ccf dC c

−r c

−rc=k Cc2

Where


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C c0 = Initial Concentration of Carbon

C cf = Final Concentration of Carbon

X cf = Fractional Conversion of Caron

Suppose Conversion of Carbon is 90%

So

X c = 0.90

Mass flow rate of Carbon = 2.791 Kg/s

As1Kg of wood contains = 0.506Kg of Carbon2.791kg/sec x 1kmol/12kg = 0.2326 K mole/s of carbon=836.36 Kmol/hr

To convert it into volumetric flow rate, we divided it with density of carbon (graphite), that is Density of Carbon = 2000 Kg/m3

As,Volumetric flow rate = Mass flow rate/ Density

So,

Volumetric flow rate of carbon = 2.791Kg/s / 2000Kg/m3 x3600s/1h

= 5.0238 m3/hVolumetric flow of wood = 5.5158 Kg/s

So,Initial concentration of C = 836.36/5.0237= 166.67 Kmol/m3Final concentration =?

C c=C c0

(1−X c)(1+ε c Xc )

Whereε c = fractional change in volume

ε c=V f−V 0

V 0

ε c=2−2

2=0

We getFinal Concentration = 16.667 Kmol/m3

Now rate equation for reaction

C+ H2O CO+ H2

−rc=k Cc2=kc [ C ] [H 2 O ]


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Where[Cc] = final concentration of carbon[H2O] = concentration of H2OKc = rate constant

So,−rc=kc [C ] [H 2 O ]

We know the value of [C], but we do not know [H2O]The value of k comes out to be 0.11from literature[g]. Considering the rate equation in

terms of concentration.As we know

PV = nRTN/V = P/RTconc. = P/RTSo of H2O,[H2O] = P/RT

As steam is entering atP = 101.325 kpaT = 300 °C = 573 K

So by putting the values in above equation [H2O] = 101.325/8.314x573

= 0.021 Kmol/m3

So-rc=0.11x0.021x16.667-rc = 0.0385 kmol/m3 sec

Now

6.8-Residence time = t [h] :-

t=C c∫0

0.9 dX c

−r c

t = 389 s = 6.49 min

6.9-Volume of solid [h] :- To find the volume of solidFor plug flow reactor, we know that

t=C c 0V

Fc 0

F c0 = Flow rate of Carbon in feedV = VolumeC c0 = initial Concentration of carbon


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V=389.65∗0.232616.667

V = 5.45 m3

6.10-Volume of Product Gas:-Flow rate of product gas out

PV = nRTVg = nRT/Pn = flow rate of product gas out of gasifier

From this, mass balance datan = 0.018 Kmol/sP = 101.325 KpaR = 8.314 Kpa m3/kmol.kT = 573.0 K

Putting the values,Vg = nRT/P= (0.018 x 8.314 x 573)/101.325Vg= 17.33 m3

6.11-Volume of the Gasifier:-Total Volume = volume occupied by solid + volume occupied by product Gas= 5.45 + 17.33Total volume = 22.78 m3

6.12-Diameter of Gasifier:-Total Volume of Gasifier = 22.78 m3Area x length = 22.78 m3πD2 /4 x L = 22.78 m3 Normally L/D ratio lies b/w 3 – 6 so,Assume L/D = 6.0[j]

HenceL = 6D put in above equationπD2 /4 x 6D = 22.78π6 /4 x D3 = 22.784.71 D3 = 22.78Diameter of gasifier = 1.68mLength of gasifier = 1.68 x 6Length of gasifier =10.08 m

A vessel must be designed to withstand the maximum pressure to which it is likely to be subjected in operation.


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6.13-Minimum wall thickness:- t = PR/SE-0.6P + Tc[i]

Wheret= reactor wall thickness in inchesP= design pressure difference between inside and outside of reactor, psigR= inside radius of steel vessel in inches= 1.68/2=0.84m=39.37x0.84=33.07inS= maximum allowable stress for the steel[k]. E= joint efficiency (≈0.9)Tc=corrosion allowance = 0.125 in.By using stainless steel pipeS=1200 PsiBy putting the values in above equation

t = 14.7x33.07/(1200x0.9)-(0.6x14.7)+0.125 t = 486.13/ (1080-8.82) +0.125 t = 0.576 inches=25.4x0.576=14.63 mm


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7-Fluidization[n]The phenomena in which bed of solid particle is fluidized, when the gas or liquid is

pass through it with the velocity that will be able to make solid particles, to behave like fluid.

The concept is depends upon the pressure drop and drag force. When the liquid or gas is pass through the bed of solid particles the pressure drop occur and the fluid exert drag force on the solid particles, the particles do not move but, if the velocity of the fluid steadily increased, the pressure drop and drag force on the particle increases till the point reach at which the particle starts to move and they become suspended in the fluid. This process is called fluidization. It has advantage for solid handling.

The fluid velocity depends upon the density of suspended particles, its porosity and sphericity.

7.1-Conditions for fluidization:-

The height and the pressure drop of the fluidized depends upon the velocity of the fluid entering the bed. If we draw the graph between pressure drop and bed height following graph occur.

In the fluidized bed reactor upper portion is kept open or connected with cyclone separator. At the lower side of the bed the distributor plate is place to support the bed and to distribute the fluid to the entire bed. If the particle in the bed are small, the flow pattern of the fluid is laminar while passing through the channels of the bed and the pressure drop across the bed is directly proportional to the superficial velocity V0.

When the fluid having the low velocity passes through the distributor plate, the solid particles will not move and bed height is remains same as shown in graph. But if we go on increase the velocity of the fluid, the particles will slight able to move and pressure drop increases, this is the point A in the figure. After that the particles shows minimum fluidization and height of the bed going to be change. When particles are fluidized the pressure drop across the bed remains constant. At the fluidization of the particles the bed height changes and that is the point BC on the graph. When the pressure


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drop remains constant at fluidization, if we go on decreasing the velocity of the fluid the bed height decreases that is the point BC on the graph.

The point at which the particles begins to move is the minimum fluidization velocity V0M.

The maximum velocity of fluid at which particles begins to entrain out of the reactor is called Terminal Fluidization Velocity VT. The fluidization velocity is selected between minimum and terminal Fluidization velocity.


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8-Design of the Fluidized bed8.1-Parameter:-

Bed Height Bed Area

8.2-Assumptions:-

Density of Steam [o] (850 0C, 1 atm) = ρs = 0.41 kg/m3

Viscosity of Steam (850 C, 1 atm) = µ = 0.0000404 pa.s

Property[n][p][r] Nickel Olivine Catalyst SawdustMean Particle Size (µm) 350 1000Apparent Density (kg/m3) 1755 215Porosity (Ɛ) 0.48 0.7Sphericity (ϕ) 0.8 0.5True Density (kg/m3) 3250 717

Apparent Density [r]

ρapp= ρtrue(1−ε )

In order to find the area of the fluidized bed, following parameters should be known

Minimum Fluidization Velocity Vmf

Terminal Fluidization Velocity VT

Fluidization velocity

Consider the flow of fluid between the channels of particle is laminar for minimum Re.

8.3-Minimum Fluidization velocity [q] :-

V f =d p

2 . g . ε3 .∅ 2(ρ p−ρs)150.μ .(1−ε )

Ni/O Catalyst Sawdust

Minimum Fluidization Velocity (m/s)

0.05 0.1


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8.4-Terminal Fluidization Velocity [q] :-

V T

V mf

=8.33(1−ε )

∅ 2 . ε3

Ni/O Sawdust

Terminal Fluidization Velocity (m/s)

3.1 2.91

To select the Fluidization Velocity the correlation is given in the (Chatterjee et al 1995) in the form of height. But if we select fluidization velocity 3 m/s by considering the minimum and maximum fluidization velocity of the particle we might able to find the ratio of Expanded Bed Height H and minimum Bed Height Hmf.

HHmf

=1+10.978 (V f −V mf )

0.738 . ρp0.376 . d p

1.006

V mf0.937 . ρ s

0.126

So the bed height for both the particles is

Ni/O Catalyst Sawdust

Bed height ratio 3.21 1.6

Hence with the allowance bed height ratio is selected

HHmf

=4

8.5-Area of the Fluidized Bed [r] :-

To find the Cross Sectional area of the Fluidized Bed.

Ab=Volumetric Flow rate of Product Gas

FluidationVelocity

Ab=V b

V f

Ab=7.937

3=2.6457 m2


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9-Conclusion:- Study of circulating fluidized bed (20MW-100MW) in the presence of Nickel-Olivine catalyst reveals that for 100 MW of wood, wood to steam ratio is 0.6-0.7 which further leads to make an estimate of the flow rate of feed. So, flow rate of wood is 5.515kg/s fed from the top of the reactor and steam required for the gasification of 5.515kg/s is 3.8605kg/s which after conversion of 90% of wood produces 4.9635kg/s of syngas with production of Ash 0.077kg/s. Here, the density of wood can be considered as a bulk or apparent to find out the volumetric flow rate for the reactor. The various parameters of circulating fluidized bed like volume of solids which is 5.45m3,volume of product gas Vg is 17.33m3 ,total volume of gasifier 22.78m3,diameter of gasifier is 1.68m, length of the reactor is 10.08m, wall thickness of reactor is 14.63mmand residence time for the reaction is 6.49 min designed from above discussed basis.in the design of fluidized bed we calculate the bed height and bed area also the minimum fluidized velocity for catalyst is 0.05 and for wood 0.1 and terminal velocity of catalyst is 3.1 and for wood it is 2.91. By the study of mean particle size of wood and catalyst, porosity of wood and catalyst and sphericity of both. The bed height is 3.21 for catalyst and for wood it is 1.6.


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10-References:-1) http://www.sciencedirect.com/science/article/pii/S096195340900230X 2) http://www.sciencedirect.com/science/article/pii/S0961953402001022 3) http://theurbanfarmingguys.com/wiki/Wood_Gasification 4) http://www.fao.org/docrep/t0512e/t0512e0a.htm 5) http://books.google.com.pk/books?id=2-

G0SaWM80oC&pg=PA36&lpg=PA36&dq=difference+between+the+entrained+gasifier+and+draught+gasifier&source=bl&ots=8iYL6un9AN&sig=9EgwsIM-UsbrHeE-pz3R9XKAnP8&hl=en&sa=X&ei=KqXSUuyYKYyr0AWti4D4BA&ved=0CDkQ6AEwAw#v=onepage&q=difference%20between%20the%20entrained%20gasifier%20and%20draught%20gasifier&f=false

6) http://en.wikipedia.org/wiki/Gasification#Co- current_fixed_bed_.28.22down_draft.22.29_gasifier

7) http://en.wikipedia.org/wiki/Gasification 8) http://www.nariphaltan.org/Gasifier.pdf 9) http://www.gasification-freiberg.org/PortalData/1/Resources/documents/paper/IFC_2010/06-

2-Pugsley-Mahinpey.pdf10) http://www.amracenter.com/doc/pubblicazioni/11i.flugas.pdf 11) http://www.google.com.pk/patents?

hl=en&lr=&vid=USPAT4183208&id=VTk0AAAAEBAJ&oi=fnd&dq=fluidized+bed+gasifier&printsec=abstract#v=onepage&q=fluidized%20bed%20gasifier&f=false

12) http://books.google.com.pk/books? id=bFT204XDTQ0C&pg=PA1&lpg=PA1&dq=difference+between+bubbling+and+circulating+fluidized+bed+of+gasifier&source=bl&ots=CvCyyxLnia&sig=MX0TxOs0k48RC_KijZwA2YCyQs4&hl=en&sa=X&ei=FsLSUsbXDpCrhAfTn4CQBQ&ved=0CDIQ6AEwAg#v=onepage&q=difference%20between%20bubbling%20and%20circulating%20fluidized%20bed%20of%20gasifier&f=false

13) https://www.google.com/search? site=imghp&tbm=isch&source=hp&biw=1280&bih=708&q=fixed+bed+gasifier&oq=fixed+bed&gs_l=img.3.3.0l10.1640.4688.0.8340.9.9.0.0.0.0.381.1476.3j2j3j1.9.0....0...1ac.1.32.img..2.7.892.wmUmKk5Tecw#q=fixed+bed+gasifier+for+wood&tbm=isch&facrc=_&imgdii=_&imgrc=7kG45g37_fynoM%253A%3BjfL02vsAxotFoM%3Bhttp%253A%252F%252F4.bp.blogspot.com%252F-tR3S_E9yUF0%252FURjzIG7xWpI%252FAAAAAAAAAEk%252F1QlgkBdPT-g%252Fs1600%252Fgasifier.jpg%3Bhttp%253A%252F%252Fmechentropy.blogspot.com%252F%3B578%3B301

14) http://www.fao.org/docrep/t4470e/t4470e0m.htm 15) http://www.eco-innovation.eu/index.php?option=com_content&view=article&id=624:bosio-

doo&catid=73:slovenia16) http://www.ncbi.nlm.nih.gov/pubmed/11590739 17) http://www.ficfb.at/


http://www.ficfb.at/

http://www.ncbi.nlm.nih.gov/pubmed/11590739

http://www.eco-innovation.eu/index.php?option=com_content&view=article&id=624:bosio-doo&catid=73:slovenia

http://www.eco-innovation.eu/index.php?option=com_content&view=article&id=624:bosio-doo&catid=73:slovenia

http://www.fao.org/docrep/t4470e/t4470e0m.htm

https://www.google.com/search?site=imghp&tbm=isch&source=hp&biw=1280&bih=708&q=fixed+bed+gasifier&oq=fixed+bed&gs_l=img.3.3.0l10.1640.4688.0.8340.9.9.0.0.0.0.381.1476.3j2j3j1.9.0....0...1ac.1.32.img..2.7.892.wmUmKk5Tecw#q=fixed+bed+gasifier+for+wood&tbm=isch&facrc=_&imgdii=_&imgrc=7kG45g37_fynoM%253A%3BjfL02vsAxotFoM%3Bhttp%253A%252F%252F4.bp.blogspot.com%252F-tR3S_E9yUF0%252FURjzIG7xWpI%252FAAAAAAAAAEk%252F1QlgkBdPT-g%252Fs1600%252Fgasifier.jpg%3Bhttp%253A%252F%252Fmech



http://books.google.com.pk/books?id=bFT204XDTQ0C&pg=PA1&lpg=PA1&dq=difference+between+bubbling+and+circulating+fluidized+bed+of+gasifier&source=bl&ots=CvCyyxLnia&sig=MX0TxOs0k48RC_KijZwA2YCyQs4&hl=en&sa=X&ei=FsLSUsbXDpCrhAfTn4CQBQ&ved=0CDIQ6AEwAg#v=onepage&q=difference%20between%20bubbling%20and%20circulating%20fluidized%20bed%20of%20gasifier&f=false



http://www.google.com.pk/patents?hl=en&lr=&vid=USPAT4183208&id=VTk0AAAAEBAJ&oi=fnd&dq=fluidized+bed+gasifier&printsec=abstract#v=onepage&q=fluidized%20bed%20gasifier&f=false



http://www.amracenter.com/doc/pubblicazioni/11i.flugas.pdf

http://www.gasification-freiberg.org/PortalData/1/Resources/documents/paper/IFC_2010/06-2-Pugsley-Mahinpey.pdf

http://www.gasification-freiberg.org/PortalData/1/Resources/documents/paper/IFC_2010/06-2-Pugsley-Mahinpey.pdf

http://www.nariphaltan.org/Gasifier.pdf

http://en.wikipedia.org/wiki/Gasification

http://en.wikipedia.org/wiki/Gasification#Co-current_fixed_bed_.28.22down_draft.22.29_gasifier

http://en.wikipedia.org/wiki/Gasification#Co-current_fixed_bed_.28.22down_draft.22.29_gasifier

http://books.google.com.pk/books?id=2-G0SaWM80oC&pg=PA36&lpg=PA36&dq=difference+between+the+entrained+gasifier+and+draught+gasifier&source=bl&ots=8iYL6un9AN&sig=9EgwsIM-UsbrHeE-pz3R9XKAnP8&hl=en&sa=X&ei=KqXSUuyYKYyr0AWti4D4BA&ved=0CDkQ6AEwAw#v=onepage&q=difference%20between%20the%20entrained%20gasifier%20and%20draught%20gasifier&f=false



http://www.fao.org/docrep/t0512e/t0512e0a.htm

http://theurbanfarmingguys.com/wiki/Wood_Gasification

http://www.sciencedirect.com/science/article/pii/S0961953402001022

http://www.sciencedirect.com/science/article/pii/S096195340900230X

28 | P a g e

18) http://www.netl.doe.gov/technologies/coalpower/turbines/refshelf/handbook/1.2.1.pdf 19) Biomass Gasification and Pyrolysis, Practical Design and Theory by Prabir Bassu.

a) Prabir Bassu, Biomass Gasification and Pyrolysis Practical Design and Theory, chapter 2, page 58

b) Prabir Bassu, Biomass Gasification and Pyrolysis Practical Design and Theory, chapter 2, page 51 table 2.8

c) The study of reactions influencing the biomass steam gasification process http://www.sciencedirect.com/science/article/pii/S0016236102003137

d) http://www.gabrieljebb.com/media/whitepaper/week5/research/Chemistry%20of%20Wood%20Gasification.pdf]

e) Theory of gasification http://www.fao.org/docrep/t0512e/t0512e09.htm (all reactions)f) Chemical Reaction Engineering by Levin spiel page 92 (PFR equation)g) Combustion and gasification in fluidized bed by prabir Bassu page 68 (Value of k)h) Chemical Reaction Engineering by Levin spiel Chapter 5 section 5.2 ( volume of solid &

residence time)i) S,S&L Chapter 7 Terry A. Ring ChE (wall thickness equation)j) http://www.google.nl/patents/US4828581(h/d ratio)k) http://www.engineeringtoolbox.com/temperature-allowable-stresses-pipes

d_1338.html(allowable stress ) l) http://www.researchgate.net/publication/

256569410_Prospects_for_coal_gasification_in_Pakistanm) Biomass gasification By Anil K. Rajvanshin) McCabe, Smith, Harriott “Unit Operation of Chemical Engineering”,edition 7th , pg # 177o) M. Smith, Van Ness, Abott “Introduction to Chemical Engineering Thermodynamics”

Edition 7th p) Perry Chemical Engineeringq) J.Ramirez, J. Martinez, L Petro, “Basic Design of Fluidized Bed Gasifier For Rice Husk

on Pilot Scale”r) Prabir Basu “Biomass Gasification and Pyrolysis, Practical Design”s) D. Kunii, O. Levenspiel “Fluidization Engineering”,1991t) Gomez Barea, Campoy M, Ollero P. Fernandez C “Pilot Plant Experiences with

Fluidized bed Gasification of Orujillo and MBM”u) http://books.google.com.pk/books?

id=GzKmQnrdXm0C&pg=PA512&lpg=PA512&dq=olivine+porosity&source=bl&ots=ygTd9SYuK1&sig=jR7PFlBqvsxoIcNQDcm8ulRnXGQ&hl=en&sa=X&ei=aXfTUvzyGueZ0QXe5IHwBA&ved=0CEwQ6AEwBw#v=onepage&q=olivine%20porosity&f=false


http://books.google.com.pk/books?id=GzKmQnrdXm0C&pg=PA512&lpg=PA512&dq=olivine+porosity&source=bl&ots=ygTd9SYuK1&sig=jR7PFlBqvsxoIcNQDcm8ulRnXGQ&hl=en&sa=X&ei=aXfTUvzyGueZ0QXe5IHwBA&ved=0CEwQ6AEwBw#v=onepage&q=olivine%20porosity&f=false



http://www.engineeringtoolbox.com/temperature-allowable-stresses-pipes%20d_1338.html(allowable

http://www.engineeringtoolbox.com/temperature-allowable-stresses-pipes%20d_1338.html(allowable

http://www.fao.org/docrep/t0512e/t0512e09.htm

http://www.sciencedirect.com/science/article/pii/S0016236102003137

http://www.netl.doe.gov/technologies/coalpower/turbines/refshelf/handbook/1.2.1.pdf

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