Renewable and Non - Renewable Reosources

RENEWABLE AND NON – RENEWABLE
ENERGY RESOURCES
Dr. Neeraj Yadav
Assistant Professor
School of Basic and Applied Science
K. R. Mangalam University

Resources:
All things that are useful to us are called resources. Resources are useful raw materials that we get from nature. These
are naturally occurring materials.

Resources
CLASSIFICATION OF RESOURCES:
That can be replenished or
renewed naturally over
time.
That are available in limited quantity. These
resources cannot be renewed or replenished in
short duration. Therefore they are also known
as exhaustible resources.

SOLAR ENERGY:
➢ Directly or indirectly sun is the main source for all of the energy on the earth.
➢ The nuclear fusion reactions occurring inside the sun releases enormous quantity of energy in form of heat and light.
➢ The solar energy received by the earth space is 1.4 KJ/s/m2, known as solar constant.
➢ Examples: Solar cells: Also known as photovoltaic cell.
➢ Made up of thin wafers of semi conductors materials like Si,
Ga. When solar radiations fall on them, a potential difference
is produced which cause flow of electrons and produces
electricity. The potential difference produced by a single
solar cell is 0.4-0.5volts and produces a current of 60 mA.

SOLAR COOKER:
➢ Solar cooker make use of solar heat by reflecting solar radiations using a mirror directly on to glass sheet which
cover black insulated box within raw food.
➢ Now a days, solar cooker is now available having concave reflector results in more heating effect and greater
efficiency.

SOLAR WATER HEATER:
➢ Insulated box painted black from inside having copper coil through which cold water is made flow in .
➢ Get heated and flow out into the storage tank.
➢ The hot water from the storage tank fitted on the roof top is then supplied through pipes into the buildings.

2. HYDRO-ENERGY:
➢ Water flowing into the river or water stored in a dam is sources of hydro energy and allowed to fall from a height.
The Simple method to use hydro energy is to convert it into electrical energy.
➢ The blades of the turbine located at the bottom of the dam move with the
fast moving water which in turn rotate the generator and produces electricity.
➢ Till now we have utilized only a little more than 11% of this
potential.
➢ Hydropower does not cause any pollution, it is renewable and
normally the hydro power projects are multi-purpose projects
helping in controlling floods, used for irrigation, navigation etc.

3. WIND ENERGY
➢ In India, many windmills have been set up in different places such as Tamil Nadu, Maharashtra, Rajasthan, Kerala,
West Bengal and Gujarat. The largest wind farm of our country is near Kanyakumari in Tamil Nadu generating 380
MW electricity
➢ The high speed winds have a lot of energy in them as kinetic energy due to their motion.
➢ The driving force of the winds is the sun.
➢ The blades of the wind mill keep on rotating continuously due to the force of
the striking wind.
➢ The rotational motion of the blades drives a number of machines like water
pumps, flour mills and electric generators.
➢ A large number of wind mills are installed in clusters called wind farms,
which feed power to the utility grid and produce a large amount of electricity.
➢ The wind power potential of our country is estimated to be about 20,000 MW,
while at present we are generating about 1020 MW.

4. BIOGAS
Biogas is a type of fuel which is a mixture of gases such as methane, carbon dioxide, hydrogen etc. which is obtained by
decomposition of animal and plant wastes like animal dung, with the help of micro-organisms in the presence of water. It
is used as fuel in gas stove especially in rural areas.
➢ The biogas plant consists of the following parts:-
1) Inlet or charge pit:- for passage of slurry into the digester.
2) Digester:- cylindrical tank which is airtight, above which is present a
floating gas holder of metal with an outlet of gas and pit for removal of
sludge.
Here the organic wastes get solubilized into simpler substances called
monomers (solubilisation). Monomers change to organic acid by fermenting microbes (acidogenesis).
Organic acid mostly formed is acetic acid.
Methanogens become active and act on components of microbial digestion and form methane gas (methanogenesis).
3) Outlet:- consists of sludge which is used as manure.

5. HYDROGEN
➢ It is a good source of energy because it does not create pollution and produce maximum energy on burning.
➢ Hydrogen has the potential to be the answer to all our energy and fuel troubles.
➢ As of 2020, the majority of hydrogen (∼95%) is produced from fossil fuels by steam reforming of natural gas,
partial oxidation of methane, and coal gasification.
• CH4 in natural gas + 1/2O2 ------------→ CO + 2H2 + Heat (Partial oxidation of methane reaction)
• CO + H2O --------------→ CO2 + H2 + small amount of heat (water gas shift reaction)
• CH4 + H2O + Heat ------------→ CO + 3H2 (steam – methane reforming reaction)
➢ Hydrogen can be used in fuel cells to generate power using a chemical reaction rather than combustion,
producing only water and heat as byproducts.
➢ It can be used in cars, in houses, for portable power, and in many more applications.

6. GEOTHERMAL ENERGY
➢ The thermal energy generated and stored in the earth (Thermal energy to determine the temp. of matter).
➢ Geothermal from Greek word geo – earth and thermos – hot.
➢ Geothermal energy of the earth’s crust originates from the original formation of planet (20%) and from the
radioactive decay of minerals (80%). It is contained in the rocks and beneath the earth’s crust.
➢ It can be found as far down to earth’s hot molten rock, magma.
➢ To produce power from geothermal energy, wells are dug a mile deep into the underground reservoir to access the
steam and hot water there, which can be used to drive turbines connected to electricity generator.
Working:
➢ Hot water is pumped from deep underground through well under high pressure
➢ When water reaches the surface, pressure is dropped which cause water to
turn into steam.
➢ The steam spins a turbine which is connected to generator that produce
electricity.
➢ The steam cools off in a cooling tower and condenses back to water.
➢ The cooled water is pumped back into the earth to begin the process again.

7. TIDAL ENERGY:
➢ It is the form of hydropower that converts the energy obtained from tides into useful forms of power, mainly
electricity.
➢ Tides are more predictable than the wind and the sun.
➢ These forces create corresponding motion or currents in the world’s oceans.
➢ Due to strong attraction, a bulge in water level is created, causing a temporary increases in sea level. When sea level is
raised, water from middle of the oceans is forced to move toward shoreline creating a tide.
➢ When the earth and moon gravity line up each other, the influence of these two gravitational
forces becomes very strong and causes millions of gallons of water to flow towards shore
creating a high tide.
➢ When the earth and moons gravity are at 90° to each other, the influence of these two
gravitational forces is weaker and the water flows away from the shore as the mass of
water moves to another location on the earth creating low tide condition.

TIDAL BARRAGE:
➢ Tidal barrages make use of the potential energy in the difference in height between high and low tides.
➢ When the sea level rises and the tide begins to come in, the temporary increase in tidal power is channelled into a
large basin behind the dam, holding a large amount of potential energy.
➢ With the receding tide, this energy is then converted into mechanical energy as the water is released through large
turbines that create electrical power through the use of generators.
➢ Barrages are essentially dams across the full width of a tidal estuary.

NON RENEWABLE RESOURCES:
➢ A substance that is being used up more quickly than it can replace itself.
➢ Its supply is finite.
➢ Examples: Most fossil fuels, natural gas, oil, coal, minerals and metal ores.
➢ They are not environmental friendly and have serious effect on our earth.

NATURAL GAS:
➢ It is a mixture of hydrocarbon compounds which are multiple combination of carbon and hydrogen atoms
containing methane and higher hydrocarbons like butane, propane in varying amount.
➢ Natural gas is the earth’s cleanest burning hydrocarbon:
1. Natural gas has the cleanest combustion profile of all the fossil fuels as it has high calorific value of about
50KJ/G and burns without smoke. .
2. The main product of the combustion of natural gas are CO2 and water vapors and does not produce ash
residues, SO2.
➢ It is formed organically over millions of the years from decomposing plant and animal matter that is buried in
sedimentary rock layers. Once formed the gas tends to migrate through the pore space, fractures and fissures in the
sediments and rocks.
➢ Raw natural gas come from three types of wells: oil wells, gas wells and condensate wells.
➢ Raw natural gas may contain some mixture of butane, propane and pentane gases as well as nitrogen, CO2 and
water vapors but methane is primary component.

NATURAL GAS:
➢ It is a mixture of hydrocarbon compounds which are multiple combination of carbon and hydrogen atoms
Main components: Methane – 70 – 90%
Ethane, propane, butane – 0 – 20%
Water vapors, hydrogen sulphide, CO2, nitrogen and helium - < 10%
➢ The natural gas composition depends on the chemical composition of decomposed materials of plants and animals.
BENEFITS OF NATURAL GAS: Natural gas is a non-renewable hydrocarbon used as a source of energy
for
➢ heating, cooking, and electricity generation.
➢ It is also used as a fuel for vehicles and
➢ as a chemical feedstock in the manufacture of plastics and other commercially important organic chemicals.

DIFFERENCE BETWEEN DRY NATURAL GAS AND WET NATURAL GAS:
Dry Natural gas Wet Natural gas/ Liquid Natural gas
Almost completely methane. Higher the concentration of
methane, drier it will be.
Ethane or butane. Methane content is lower.
Dry natural gas is what remains after removing liquified
hydrocarbon and non – hydrocarbon.
The combination of LNG and liquified
hydrocarbons gives it the wetness.
Typically used in heating and cooling system, electric
power generation. Once compressed, dry gas can be used
as vehicle fuel.
Used in refrigeration and freezing system, in
torches for cooking purposes and as fuel for
lighters and grills

NATURAL GAS (CONT……):
➢ It can be easily transported through pipelines.
➢ Russia has maximum reserve (40%)followed by Iran (14%) and USA (7%).
➢ In India, it is found in Tripura, Jaisalmer, off-shore area of Mumbai and Krishna Godavari Delta.
COMPRESSED NATURAL GAS (CNG):
➢ It is being used as an alternative of petrol and diesel for transport of vehicles.
➢ It can be used in place of gasoline and liquified petroleum gas (LPG).
➢ CNG is made by compressing natural gas which is mainly composed of methane, to less than 1% of its volume at
standard atmospheric pressure.
SYNTHETIC NATURAL GAS: (SNG):
It is mixture of CO and H2. it is connecting between fossil fuels and substituted gas by gasification followed by catalytic
conversion of methane.

LIQUIFIED PETROLEUM GAS:
➢ It is flammable mixture of hydrocarbon gases used as fuel in heating appliances, cooking equipment and vehicles.
➢ It is increasingly used as aerosol propellant and refrigerant replacing CFC in an effort to reduce to damage of Ozone
layer.
➢ It mainly contains mixture of propane and butane.
➢ It is prepared by refining petroleum or wet natural gas and is almost derived from fossil fuels sources.

CRUDE OIL/ PETROLEUM:
➢ Crude oil is a nonrenewable resource that builds up in liquid form between the layers of the Earth's crust.
➢ It's retrieved by drilling into the ground and ocean floor, and pumping the liquid out. The liquid is then refined by
fractional distillation and used to create many different products such as petroleum gas, kerosene, fuel oil, lubricating
oil paraffin wax, plastics, artificial food flavorings, heating oil, petrol, diesel, jet fuel, and propane. .
➢ There are three countries in the world having 67% of the petroleum reserve which together form OPEC
(Organization of Petroleum Exploring Countries). The top three oil-producing countries are Russia, Saudi Arabia,
and the United States.
➢ It is a complex mixture of alkane hydrocarbon.
➢ The basic step in harnessing energy from petroleum include exploration of oil resources, drilling of wells, production,
storage and transport of crude oil, refining if crude oil, storage and transportation of products.

➢ Drilling is done from specifically formed drilling platform. For enhanced extraction, the following techniques are used:
• By injecting fluid (air, gas, steam, water) into the well.
• By using chemical explosives to loosen tight formations.
• By adding chemicals to reduce viscosity of the crude oil.
• By allowing microbial growth inside to increase bulk, reduce viscosity and enhance recovery, known as Microbially
Enhanced Oil Recovery (MEOR).
• By controlled underground burning to push up oil.
After extraction, crude oil is separated from natural gas and water, stored and transported through pipelines or tankers.
Crude oil is refined by the following processes:
• Separation of some components by distillation.
• Chemical purification or removal of impurities by adsorption (on charcoal).
• Formation of hydrocarbons by cracking or hydrogenation.
Petroleum is a cleaner fuel as compared to coal as it burns completely and leaves no residue.
It is also easier to transport and use. That is the reason why petroleum is preferred amongst all the fossil fuels.

NUCLEAR ENERGY
➢ is known for its high destructive power as evidenced from nuclear weapons.
➢ Nuclear energy can be generated by two types of reactions:
(I) NUCLEAR FISSION: It is the nuclear change in which nucleus of certain isotopes with large mass numbers are
split into lighter nuclei on bombardment by neutrons and a large amount of energy is released through a chain
reaction.
92U235 + 0n1 ------------→ 36Kr92 + 56Ba141 + 3 0n1 + Energy
Nuclear reactors make use of nuclear chain reaction. In order to control the rate of fission, only 1 neutron released is
allowed to strike for splitting another nucleus. Uranium-235 nuclei are most commonly used in nuclear reactors.
(II) NUCLEAR FUSION: Here two isotopes of a light element are forced together at extremely high temperatures
(1 billion ºC) until they fuse to form a heavier nucleus releasing enormous energy in the process. It is difficult to initiate the
process but it releases more energy than nuclear fission

Two hydrogen-2 (Deuterium) atoms may fuse to form the nucleus of Helium at 1 billion ºC and release a huge
amount of energy. Nuclear fusion reaction can also take place between one Hydrogen-2 (Deuterium) and one
Hydrogen-3 (Tritium) nucleus at 100 million ºC forming Helium-4 nucleus, one neutron and a huge amount of
energy.
The nuclear power plants are located at
❖ Tarapur (Maharashtra),
❖ Rana Pratap Sagar near Kota (Rajasthan),
❖ Kalpakkam (Tamil Nadu), Narora (U.P.),
❖ Kakrapar (Gujarat),
❖ Kaiga (Karnataka),
❖ Rawatbhata (Rajasthan) and
❖ Kudankulum (Tamil Nadu).

COAL:
➢ Coal, also called black gold, is the most abundant fossil fuel in the world.
➢ Coal contain carbon, volatile matter, moisture and ash.
➢ Coal reserves are six times greater than oil and petroleum reserves.
FORMATION OF COAL:
Coal was formed 255–350 million years ago in the hot, damp regions of the earth during the carboniferous age.
The ancient plants along the banks of rivers and swamps were buried after death into the soil and due to the heat and
pressure gradually got converted into peat and coal over millions of years.
The coal forms from the accumulation of plant debris, usually in swamp environment.
When a plant dies and fall into the swamp, the standing water protects it from decay.
To form a thick layer of plant debris required to produce a coal seam, the rate of plant debris accumulation must be
greater than rate of decay.

➢ Once a thick layer of plant debris is formed, it must be buried by sediments
➢ such as mud or sand.
➢ These are typically washed into the swamp by a flooding river.
➢ The weight of these materials compacts the plant debris and aids in its
➢ transformation into coal.
➢ Heat and pressure produced chemical and physical changes in the plant layers
which forced out oxygen and left rich carbon deposits. In time, material that
had been plants became coal.
➢ About ten feet of plant debris will compact into just one foot of coal.
➢ Plant debris accumulates very slowly. So, accumulating ten feet of plant
➢ debris will take a long time. The fifty feet of plant debris needed to make a
➢ five-foot thick coal seam would require thousands of years to accumulate.
➢ During that long time, the water level of the swamp must remain stable.
➢ If the water becomes too deep, the plants of the swamp will drown, and if the water cover is not maintained the
plant debris will decay.
➢ To form a coal seam, the ideal conditions of perfect water depth must be maintained for a very long time.

TYPES OF COAL: Coal are classified into three categories on the basis of amount of C, O, H present:
1. Anthracite Coal:
➢ Best quality; hard coal having 80 to 95 per cent carbon.
➢ Semi-metallic lustre and very little volatile matter.
➢ Negligibly small proportion of moisture.
➢ Ignites slowly == less loss of heat == highly efficient.
➢ Ignites slowly and burns with a nice short blue flame. [Complete combustion == Flame is BLUE == little or no
pollutants. Example: LPG]
➢ In India, it is found only in Jammu and Kashmir and that too in small quantity.

2. Bituminous Coal:
➢ Soft coal; most widely available and used coal.
➢ Derives its name after a liquid called bitumen.
➢ 40 to 80 per cent carbon.
➢ Moisture and volatile content (15 to 40 per cent)
➢ Dense, compact, and is usually of black colour.
➢ Does not have traces of original vegetable material.
➢ Calorific value is very high due to high proportion of carbon and low moisture.
➢ Used in production of coke and gas.

3. Lignite:
➢ Brown coal.
➢ Lower grade coal having 40 to 55 per cent carbon.
➢ Intermediate stage, Dark to black brown.
➢ Moisture content is high (over 35 per cent).
➢ It undergoes SPONTANEOUS COMBUSTION [Bad. Creates fire accidents in mines]
4. Peat Coal:
➢ First stage of transformation.
➢ Contains less than 40 to 55 per cent carbon == more impurities.
➢ Contains sufficient volatile matter and lot of moisture
➢ [more smoke and more pollution].
➢ Left to itself, it burns like wood, gives less heat,
➢ emits more smoke and leaves a lot of ash.

COAL (CONT…):
➢ Major coal fields in India are Raniganj, Jharia, Bokaro, Singrauli and Godavari valley.
➢ The coal states of India are Jharkhand, Orissa, West Bengal, Madhya Pradesh, Andhra Pradesh and Maharashtra.
➢ Anthracite coal occurs only in J & K.
➢ When coal is burnt it produces carbon dioxide, which is a greenhouse gas responsible for causing enhanced global
warming.
➢ Coal also contains impurities like sulphur and as it burns the smoke contains toxic gases like oxides of sulphur and
nitrogen.
➢ Coal conversion technologies involve conversion of coal from solid form to liquid or gaseous form by coal
liquefaction and gasification, respectively.
➢ Direct burning of coal releases emissions like smoke, particulate matter, SOX, NOX, CO and CO2, whereas gaseous or
liquid fuel forms cause less pollution. Energy from petroleum is harnessed by refining and fractional distillation.

DIFFERENT USES OF COAL:
Coal is seemingly the cheapest and most essential source of energy. Here is a list of all the major uses of coal.
•Generating Electricity
•Production of Steel
•Industries
•Gasification and Liquefaction
•Domestic Use
1. Generating Electricity:
➢ Coal is generally used in thermal power generation which further helps to produce electricity.
➢ Powdered coal is burnt at high temperature which further turns water into steam.
➢ This steam is used to turn turbines at high speed in a strong magnetic field.
➢ After this, electricity is finally generated.

2. Production of Steel:
➢ In the steel industry coal is used indirectly to make steel.
➢ Coal is baked in furnaces to form coal coke.
➢ Once this is formed, manufacturers use coal coke to smelt iron ore into iron and make steel.
➢ Meanwhile, ammonia gas is usually recovered from coke ovens and this is used to manufacture nitric acid, ammonia
salts and fertilizers.
3. Industries:
➢ Many industries use coal to manufacture certain products.
➢ Some of them are the cement industry, paper and aluminium industry, chemical and pharma industry amongst others.
➢ Coal provides numerous raw materials like benozle, coal tar, sulphate of ammonia, creosote, etc. to chemical.
industries. Coal is mostly used as a source of energy is most of the industries.
4. Gasification and Liquefaction:
➢ Coal can be turned into synthetic gas which a mixture of carbon monoxide and hydrogen.
➢ These gases are an intermediate product that can be further converted into different products like urea, methanol,
pure hydrogen and more.
➢ Coal can also be turned into liquid known as synthetic fuels.

➢ These chemicals produced from coal are used primarily to make other products.
➢ Besides, most of the products out there in the market have coal or coal by-products as components.
➢ Some of them include aspirins, solvents, soap, dyes, plastics and fibres which include nylon and rayon.
5. Specialist Products
Coal is also an essential ingredient in the production of specialist products such as activated carbons, carbon fibre and
silicon metals.
6. Domestic Use
In cold regions and in developing or underdeveloped countries coal is still used as fuel for cooking and a source of heat.

COALAS FUEL TO GENERATE ELECTRICITY:
Th e - process of converting coal into electricity has multiple steps and is similar to the process used to convert oil and
natural gas into electricity:
1. A machine called a pulverizer grinds the coal into a fine powder.
2. The coal powder mixes with hot air, which helps the coal burn more efficiently, and the mixture moves to the furnace.
3. The burning coal heats water in a boiler, creating steam.
4. Steam from the boiler spins the blades of an engine called a turbine,
transforming heat energy from burning coal into mechanical energy
that spins the turbine engine.
5. The spinning turbine is used to power a generator, a machine that
turns mechanical energy into electric energy. This happens when
magnets inside a copper coil in the generator spin.
6. A condenser cools the steam moving through the turbine. As the steam is condensed, it turns back into water.
7. The water returns to the boiler, and the cycle begins again.
❑ We use coal-generated electricity for: 1. heating, 2. cooling, 3. cooking, 4. lighting, 5. transportation, 6.
communication, 7. farming, 8. industry, 9. healthcare

CARBONIZATION OF COAL:
➢ Heating of coal in the absence of air to produce coke is called its carbonization or destructive distillation.
➢ By product is called co-product.
➢ This co – product is like coke oven gas and other liquid products like tar, benzol, naphthalene, phenol etc.
Types of carbonization: Depending upon the temperature upto which coal is heated in the absence of air, there are
mainly two types of carbonization:
1. Low temperature carbonization (LTC)
2. Medium temperature carbonization (MTC)
3. High temperature carbonization (HTC)

1. Low temperature carbonization:
➢ Normally carried out in the temperature range of 500 deg C to 700 deg C.
➢ The yields of liquid products are higher
➢ There is lower gaseous product yield.
➢ The coke produced is having higher volatile matter and is free burning.
2. Medium temperature carbonization:
➢ Temperature range of around 800 deg C.
➢ This carbonization produces smokeless soft coke.
➢ By products produced are similar in characteristics to high temperature carbonization.
➢ Medium temperature carbonization is rarely practiced these days.
3. High temperature carbonization:
➢ Temperature which is above 900 deg C.
➢ Gives higher yield of gaseous products and lower yield of liquid products.
➢ This carbonization produces hard coke and is normally employed for the production of metallurgical coke from
coking coals

Bituminous Coal
Slow
Heating
Moisture, Gases
Removed
200-300°C
H2O, H2S, lower
hydrocarbon
like alkane/ alkene
formed
350°C Decomposition of Coal,
Evaluation of gases
400°C
Coking coals are formed
700°C
H2 gas eliminated
800°CFormation of Plastic
mass, Evaluation of gases
900°C
Coke is formed by
solidification of plastron
form like mass
CARBONIZATION OF COAL:

PRODUCER GAS:
➢ It is essentially a mixture of combustible gases (CO, H2) etc. associated with large percentage of non combustible gas like CO2, N2 etc.
➢ Prepared by passing air mixed with little steam (about 0.35kg/kg coal) over a hot coke maintained at 1100 °C in a special reactor
called gas producer.
➢ Consists of steel vessel about 3m dia and 4m in height.
➢ The vessel is lined inside with refractory bricks.
The producer gas production reaction can be divided into four zones:
1. Ash zone:
➢ Lowest zone consisting mainly of ash.
➢ The ash protects the grate from the intense heat of combustion.
➢ The temperature of supplied air and steam is increased as they pass
through this zone.
2. Combustion zone:
➢ Next zone to ash zone, also known as oxidation zone.
➢ Temperature of this zone is about 1100 °C where Carbon burns and form
CO andCO2.

C + O2 ---------------→ CO2 + 97 Kcal
C+ ½ O2 ---------------→ CO + 2905 Kcal
3. Reduction zone:
CO2 and steam combines with red hot coke and liberate free hydrogen and CO.
CO2 + C -------→ 2CO -36Kcal
C+ H2O -----------→ CO + H2 -29Kcal
C + 2H2O ------------------→ CO2 + 2H2 -19Kcal
4. Distillation zone:
➢ The down coming coal is heated by the out going gases.
➢ The gases give their sensible heat to coal.
➢ The heat give by the gases and heat radiated from reduction zone helps to distill the fuel.
Composition:
CO = 22-30%, H2 = 8 – 12%
N2 = 52 – 55%, CO2 = 3%, Calorific values = 1300Kcal/m3
Uses and properties:
➢ Used as cheap fuel in industry
➢ Heat treatment of furnaces
➢ Alternative of diesel as a fuel
➢ As a fuel to produce hot air in industries

WATER GAS (BLUE GAS):
➢ Mixture of combustible gases, CO and H2 with a little amount of non – combustible gases like CO2 and N2.
➢ It can be made by passing alternatively steam and little air through a bed of red hot coal or coke maintained at about 900 – 1000 °C
in a reactor which consist of steel vessel.
Reactions:
1. Supplied steam reacts with red hot coal at 900 – 1000 °C to form CO and H2.
2. The Reaction is endothermic so the temperature of bed falls:
C + H2O ------------→ CO+ H2 -29Kcal
In order to rise the coal bed at about 1000 °C, the steam supply is
temporarily blown in when following exothermic reaction occurs
C + O2 -----------→ CO2 + 97 Kcal
2C + O2 --------------→ 2CO + 59Kcal
➢ The temperature again rise the bed about 1000 °C.
➢ The cycle of steam run and air blow are thus repeated alternatively
to maintain proper temperature.

Average composition:
H2 = 51%, CO = 41%, N2 = 4% and CO2 = 4%
Uses and properties:
➢ For the production of methanol and other hydrocarbons
➢ As a fuel gas in industries
➢ As a source of hydrogen
➢ For the manufacturing of ammonia
COAL GAS:
➢ It is a mixture of CO, CH4 and H2.
➢ It is obtained during the processing of coal to get coke.
➢ Used for lighting purpose before natural gas came into use.
➢ Presently used as a fuel in some industries located near coal processing plants.

COAL GAS:
➢ It is obtained by destructive distillation of coal (It is the process of heating a complex substances such as coal in a
limited supply of air so that it break down to form simpler substances.)
➢ Coal used should be rich in volatile matter (30-40%).
➢ The process is carried out in horizontal or vertical closed iron or silica retorts at 1350 °C.
➢ The gaseous products obtained is a mixture of several combustible gases and is known as coal gas.
➢ Coke is the residue left behind.
Coal ---------------------→ Coal gas + coke (destructive distillation)
Manufacture of Coal gas:
➢ The coal gas plant consists of vertical silica retort having airtight hopper at the top.
➢ The retort is heated to about 1350 °C by the combustion of preheated producer gas and air mixture.
➢ Coal rich in volatile matter is fed to the retort through hopper which decomposes on heating.

Manufacture of Coal gas (Cont……..):
➢ The gases so produced as a result of decomposition of coal are allowed to pass through a hydraulic main to a big
water cooled condenser.
➢ Tar and ammonia get condensed and collected in two separate layers in a tar well below the condensor.
➢ The gases are then led to a scrubber under pressure with the help of exhaust pump where they are scrubbed with
water to remove last portion of tar and ammonia.
➢ The hot gases are chilled by passing them through empty tower sprayed with jets of high pressure water where
naphthalene is removed.
➢ Coal gases are then passed through another scrubber containing creosote oil.
➢ Benzene, toluene and other aromatic compounds are dissolved in oil.
➢ Gases are then passed through purifier containing trays of hydrated iron oxide and lime.
➢ Impurities like H2S, CS2, CO2 and HCN get removed.
➢ Purified coal gas is then collected in the gasholder over water from where it is supplied.

Composition of coal gas:
Methane: 32%, Hydrogen = 47% CO = 7%
Acetylene = 2% Ethylene = 3% Nitrogen = 4%
CO2 = 1% Other hydrocarbon = 4%
Properties:
➢ Colorless gas with a characteristics odour.
➢ Lighter than air
➢ Slightly soluble in water
➢ Burns with long smoky flame
➢ Poisonous in nature
➢ Calorific value is about 5000 kcal/m3
Uses:
➢ Mainly used as heating fuel
➢ As an illuminant
➢ Used to provide reducing atmosphere in metallurgical operations
➢ Also used as town gas for domestic purposes.

COAL TAR
A thick dark liquid which is a by-product of the production of coke and coal gas from coal.
It has both medical and industrial uses.
It may be applied to the affected area to treat psoriasis and seborrheic dermatitis (dandruff).
It may be used in combination with ultraviolet light therapy.
Industrially it is a railway tie preservative and used in the surfacing of roads

DESTRUCTIVE/ FRACTIONAL DISTILLATION OF COAL TAR:
➢ Destructive distillation is the chemical process involving the decomposition of feedstock by heating to a high
temperature .
➢ The process takes place in the absence of air or in the presence of limited amount of oxygen or other reagent,
catalyst or solvent such as steam or phenol.
➢ During process, the large molecules break down into smaller different compounds.
➢ The molecule distill off are generally smaller and more volatile than the feedstock molecules.
➢ Fractional distillation of tar refers to the process by which components in a chemical mixture are separated by
taking advantage of the difference in their boiling points.
➢ Distillation of coal tar is carried out mainly to produce benzols, naphtha, creosotes, naphthalene, anthracene,
carbolic and cresylic acids, pyridine and pitch.

The purpose of tar distillation is to
(i) dehydrate the tar in the dehydration column,
(ii) remove the pitch from dehydrated tar in pitch column and
(iii) separate tar oils in fractionating column.
(iv) The primary objective of coal tar distillation process is to produce a number of tar acid products from the crude tar.
The number of fractions, and size of fractions etc., which are to be taken off when tar is distilled is dependent on so many
factors such as:
1. The quality of tar plays a big part.
2. Also, the kind of plant available for distillation is an important factor.
3. The market value of the products is also important.
NOTE: Since the quality of the coal tar is dependent on the coal carbonizing process and since there are large numbers of
chemical compounds available in coal tar, the design and composition of the tar distillation plant varies with the type of tar
and the compounds which are required to be distilled.

Coal tar is distilled to give four fractions:
1. Light oil, boiling below 200 °C.
2. They are called light oil as they flow over water.
3. They are crudely fractionated then agitated with conc. H2SO4 to remove olefims.
4. The hydrocarbons are washed with dilute NaOH and redistilled to give benzene, toluene, xylene and solvent
naphtha: a mixture of indene, coumarone and their homogenous.

5. This is powerful solvent used for coating and containing coal tar and pitch.
6. This is treated with Freidal-Craft catalyst such as AlCl3, it gives coumarone – indene thermoplastioc resin, used for
cheap floor tiles, varnishes and adhesives.
➢ The middle oil boil between 200 and 250-270 °C. The most abundant chemical is naphthalene and it occurs with
phenols, cresols and pyridine in the tar.
➢ It crystallizes when the middle distillate from the tar, allowed to cool and even in this impure form is suitable for
phthalic anhydride manufacture.
➢ Alternatively, it may be purified by sublimation, a somewhat unuausl purification process.
➢ Extraction of remaining tar with aqueous NaOH takes the acidic phenols and cresols into the aqueous layer as
phenates and crystalates.
➢ They are regenerated with CO2.
➢ Heavy oil comes off between 250 and 300 °C if anthracene oil is taken off as a separate fraction but sometime they are
combined.
➢ It is wood preservative.

➢ Anthracene oil comes off between 250 and 300 – 400 °C or 350 and 400 °C if taken off as a separate fraction. It
contain anthracene, phenanthrene, carbazole and many other compounds in small quantities.
➢ It makes up about 1% of coal tar.
➢ Some 60% of the tar remains as a residue called pitch.
➢ Its production is driven by Al industry which thermally polymerizes the pitch to make electrode for the electrolysis of
molten Alumina-cryolite mixture to give Aluminium.

TAR DISTILLATION PLANT:
It consists of different sections namely:
(i) tar distillation section,
(ii) caustic washing section,
(iii) de-oiling section,
(iv) springing section, and
(v) recasting section.

➢ The crude tar stored at elevated temperature in the storage tank is drawn through crude tar filter and mixed with
caustic soda (NaOH) pumped from caustic tank by dosing pump.
➢ The mixture is pumped through tar vapour exchanger and steam-heated preheater to the bottom of the dehydration
column.
➢ In the column, the crude tar is contacted with a relatively large stream of hot dehydrated tar.
➢ The azeotropic water and oil mixture is vapourized and goes up to the top of the column and condensed in a light oil
condenser.
➢ A portion of the azeotropic light oil is sent back to the column as reflux and the remaining portion is sent to an
azeotropic distillation column.
➢ In pitch column, the dehydrated tar is mixed with a relatively large stream of hot circulating pitch.
➢ The more volatile oils in the tar are vapourized and rise up through the column.
➢ Stripping stream is injected in the column to run the operation.
➢ Crude pitch is drawn from the bottom of the column by pitch circulating pump and heated by a pipe-still heater. A part
of this pitch is put into the top of the column for contacting with the dehydrated tar.

➢ Volatile portion along with the stripping steam is recovered from the pitch column and separated into the light oil and
water fraction, a middle oil fraction, and a heavy oil fraction.
➢ The light oil and water fraction combines with the same stream from the overhead of dehydration column and are sent
to light oil condenser and then to a decanter.
➢ Middle oil flows by gravity through middle oil cooler either to middle oil buffer tank or directly to the mixing vessel in
the caustic washing section.
➢ Middle oil can be transferred from buffer tank to the caustic section as per requirement.
➢ Middle oil from the tar distillation section is counter currently contacted with a flow of 10 % NaOH solution.
➢ The system consists of three mixing vessels and three separators, situated alternatively.
➢ Middle oil, stripped of its tar acids, flows by gravity from top of the separators to the middle tank.
➢ The caustic solution, which is sodium phenolate solution mainly, after contacting with oil flows by gravity from the
bottom of the separator to phenolate tank.
➢ The sodium phenolate solution contains small amount of middle oil, which is needed to be removed to get good quality
of tar acids.
➢ Sodium phenolate solution in buffer tank is pumped via overhead exchanger into the top of the sodium phenolate
stripping column.

➢ Stripping steam is introduced at the bottom of the column which strips out the middle oil from the sodium phenolate
solution.
➢ The overhead vapour heats the incoming sodium phenolate solution and cools down.
➢ Clean sodium phenolate solution is recovered from the bottom of the stripping column and sent to the springing
section via cooler.
NOTE: The objective of springing section is to recover tar acids from sodium phenolate solution by springing with a
carbon dioxide (CO2) rich gas in a series of two packed column in counter flow.
➢ Gas is passed in upward motion through the descending sodium phenolate solution in the first column, where sodium
carbonate (Na2CO3) is formed.
➢ The bottom of the first column is introduced at the top of the second column where the stream is again contacted with
CO2 counter currently.
➢ The Na2CO3 solution is sent to a separator from the bottom of the column.
➢ Crude tar acid collected and stored in the tar acid buffer tank. CO2 rich gas is continuously bubbled through the
crude tar acid buffer tank to reduce the alkali and water content of tar acids.
➢ In the recasting section, the Na2CO3 solution from the springing section is concentrated with hard burnt lime to
produce NaOH.

➢ The crude tar acids from the tank are pumped to the primary distillation unit operated under high vacuum. During
distillation, the crude tar acids are separated into three fractions namely:
(i) crude phenol as overhead product,
(ii) crude cresol as side stream, and
(iii) crude xylenols/high boiling tar acids (HBTA) as the bottom product.
➢ The crude phenol collected in a tank from this column is pumped to a vacuum column after heating in a still.
➢ Pure phenol is collected at the top condenser.
➢ A portion of it is sent to the column as reflux.
➢ The other portion is pumped to a storage tank.
➢ The residue of this column is mixed with the crude cresol in the storage.
➢ Crude cresol from the storage tank is pumped from the storage tank into a still to preheat and then vacuum distilled
in a column.
➢ The first side fraction is o-cresol, next one is a mixture of m- and p-cresol, and the bottom product is crude
xylenol/HBTA mixture which is sent to xylenol/HBTA storage tank.
➢ Another vacuum batch distillation is carried out to recover xylenol product and HBTA.

1. Generally the first fraction to be extracted contains ammoniacal liquor, and naphtha, which is the mixture of
benzene, toluene, xylenes, and pyridine.
▪ The boiling-point range is from 80 °C to around 140 °C, and the specific gravity range is 0.87 to 0.95.
▪ The quantity of water is dependent upon the amount in the original tar, and whether it has been partially taken out
before distillation.
▪ It separates easily from the naphtha, and is drawn off from the bottom, and sent direct to the ammonia plant.
▪ A good amount of care is needed in getting off the first fraction, as frothing is very prevalent, particularly in a tar
with high free C content.
▪ The point when this danger is passed can be easily noticed by the noise which is heard inside the still, known as the
‘rattles’.
▪ When nearly all the water is off, globules of water condense on the inside of the top of the still and occasionally fall
back into the hot liquid below, to be immediately turned into vapour again with almost explosive force, with the
resulting rattling noise.

2. The second fraction is known as the light oil fraction which boils from around 140 °C to 200 °C.
▪ It has a specific gravity range of around 0.95 to 1.
▪ It contains the higher hydrocarbons of the benzene series such as mesitylene, cumenes, some naphthalene, also
phenol, and higher homologues of pyridine.
3. The third fraction is collected purely to obtain the phenol in as concentrated a state as possible, and is consequently
called the carbolic oil or middle oil fraction.
▪ It boils between 200 °C and 240 °C and has a specific gravity of 1 to 1.025, and contains phenol, cresols and higher
hydroxyl acids, much naphthalene and creosote hydrocarbons.
▪ In the distillation of this fraction, great care is required to be taken to see that the condenser water is quite hot, so
that crystallization of the naphthalene does not take place in the coils.
▪ The cold water is to be turned off in the middle of second fraction, and if the cooling water does not get warm
quickly enough, steam is to be turned into the condenser.
▪ This carbolic oil fraction is not separated, when the tar contains too small a quantity. It is sometimes found more
economical to re-distil the creosote fraction.

4. The fourth fraction is known as the creosote oil fraction.
▪ It is the largest of all fractions and contains naphthalene and heavy oils, which are aromatic hydrocarbons with a
high C and hydrogen (H2) content, and cresols and other phenol homologues.
▪ The boiling point is in the range of around 240 °C to 280 °C, and specific gravity in the range of 1.025 to 1.065.
The fifth fraction is marked by its distinctive colour, and is consequently called the green oil, yellow oil, or anthracene
oil fraction.
▪ Its specific gravity is 1.065 to 1.1, and boiling point ranges from 280 °C upwards to the end of the distillation.
▪ It contains still higher aromatic hydrocarbons, anthracene, phenanthrene, also carbazole etc.
NOTE: Numerous attempts have been made to largely increase the number of fractions taken off the tar with the idea of
better isolating the products. All these have failed, as the distillates obtained are no purer, so many complex azeotropic
mixtures being formed. Again, nothing is saved, as many of the fractions have to be mixed together again for treatment
in subsequent processes.

PROPERTIES OF COAL TAR:
• Coal tar is black in color.
• It’s a semi-solid and semi-liquid in nature and is less permeable.
• Its density is very thick and It has a peculiar smell.
• Tar is insoluble in nature which means that it can’t dissolve in water.
• It has a boiling point of 200 to 250 °C.
• Its a fuel resistant and has more temperature susceptible than asphalt cement.
USES OF COAL TAR:
1. Medicine:
▪ It demonstrates antifungal, anti-inflammatory, anti-itch, and antiparasitic properties.
▪ Coal tar is used in medicated shampoo, soap and ointment.
▪ It may be applied topically as a treatment for dandruff and psoriasis, and to kill and repel head lice.
▪ It may be used in combination with ultraviolet light therapy.

Coal tar may be used in two forms:
❖ crude coal tar (Latin: pix carbonis) or
❖ a coal tar solution (Latin: liquor picis carbonis, LPC) also known as liquor carbonis detergens (LCD).
2. Construction:
➢ Coal tar was a component of the first sealed roads.
➢ In its original development by Edgar Purnell Hooley, tarmac was tar covered with granite chips.
➢ Later the filler used was industrial slag. Today, petroleum derived binders and sealers are more commonly used.
➢ Coal tar is incorporated into some parking-lot sealcoat products used to protect the structural integrity of the underlying
pavement.
➢ Sealcoat products that are coal-tar based typically contain 20 to 35 percent coal-tar pitch.
➢ Research shows it is used in United States states from Alaska to Florida.

3. Industry:
➢ Being flammable, coal tar is sometimes used for heating or to fire boilers
➢ A large part of the binder used in the graphite industry for making "green blocks" is coke oven volatiles (COV), a considerable
portion of which is coal tar.
➢ Coal tar is also used to manufacture paints, synthetic dyes (notably tartrazine/Yellow #5), and photographic materials.
➢ In the coal gas era, there were many companies in Britain whose business was to distill coal tar to separate the higher-value fractions,
such as naphtha, creosote and pitch. A great many industrial chemicals were first isolated from coal tar during this time. These
companies included:
▪ British Tar Products
▪ Lancashire Tar Distillers
▪ Midland Tar Distillers
▪ Newton, Chambers & Company (owners of Izal brand disinfectant)
▪ Sadlers Chemicals

WHAT IS METALLURGICAL COKE?
➢ Metallurgical coke is made from low ash, low sulfur bituminous coal, with special coking properties, which is
inserted into ovens and heated to 1000F to fuse fixed carbon and inherent ash and drive off most of the volatile
matter.
➢ The final product is a nearly pure carbon source with sizes ranging from basketballs (foundry coke) to a fine powder
(coke breeze).
➢ Metallurgical coke must have high strength to support heavy loads in the blast furnace without disintegration.
METALLURGICAL COKE:
➢ Metallurgical coal is a special types of coal used to make Metallurgical coke .
➢ There are two types of Metallurgical coal used to make coke:
▪ Hard Coking Coal
▪ Semisoft Coking Coal
➢ These types of coal are ideal for coke because they melt, swell and re – solidify when placed into superheated
furnace

➢ These types of coal have low level of impurities.
➢ A third type of Metallurgical coal is PCI (pulverized coal injection) which is used sometime in steel or iron making to
replace more expensive coke.
USES:
➢ Met coke is used in products where a high quality, tough, resilient carbon is required.
➢ Met coke, limestone, and iron ore are mixed together in high temperature furnaces where extreme heat causes the
chemical properties to bond, forming iron and steel.
➢ More than 95% of the met coke produced is used in the iron and steel industries.

COAL GASIFICATION
➢ Coal gasification offers one of the most versatile and clean ways to convert coal into gas, hydrogen, and other valuable
energy products.
➢ The Gasification process make possible to separate the good parts from the bad, and select the parts you want to keep.
➢ Gasification avoids burning coal altogether: it turns coal into gas.
➢ One of the major environmental opportunities of this technology is the fact that impurities can be almost entirely
filtered out when coal is transformed from a solid into a gas.
➢ Historically, coal was gasified to produce coal gas, also known as "town gas".
➢ Coal gas is combustible and was used for heating and municipal lighting, before the advent of large-scale production of
natural gas from oil wells.

In a gasifier, the carbonaceous material undergoes several different processes:
1. The dehydration or drying process occurs at around 100°C.
Typically the resulting steam is mixed into the gas flow and may be involved with subsequent chemical reactions,
notably the water-gas reaction if the temperature is sufficiently high enough.
2. The pyrolysis process occurs at around 200-300°C. Volatiles are released and char is produced, resulting in up to 70%
weight loss for coal.
The process is dependent on the properties of the carbonaceous material and determines the structure and
composition of the char, which will then undergo gasification reactions.
3. The combustion process occurs as the volatile products and some of the char reacts with oxygen to primarily form
carbon dioxide and small amounts of carbon monoxide, which provides heat for the subsequent gasification reactions.
The basic reaction here is, C+O2→CO2

4. The gasification process occurs as the char reacts with carbon and steam to produce carbon monoxide and hydrogen,
C+H2O→ H2+CO
5. In addition, the reversible gas phase water-gas shift reaction reaches equilibrium very fast at the temperatures in a
gasifier. This balances the concentrations of carbon monoxide, steam, carbon dioxide and hydrogen.
CO+H2O↔ H2+CO2
➢ The principle of catalytic synthetic production of methane from carbon monoxide and hydrogen was discovered in
1902 by Sabatier and Senderens. It is described by the CO methanation reaction:
CO+ 3H2 ↔CH4+H2O …………..…. (1)
➢ Carbon dioxide can also be converted to methane according to the following reaction
CO2 + 4H2 ↔CH4+2H2O ………….. (2)
➢ Both reactions are linked by the water gas shift conversion, which is always observed simultaneously whenever active
catalysts are used:
CO +H2O↔CO2+H2 ………………… (3)

HYDRO GASIFICATION
▪ The hydrogasification process uses H2 to gasify coal where H2 reacts with coal to produce CH4.
▪ The hydrogasification process is exothermic in nature.
▪ H2 required for the gasification is either provided by an external source or by using a methane steam reformer.
▪ A portion of the CH4 generated in the hydrogasification reactor is converted into CO and H2 in the methane steam
reformer.
▪ The hydrogasification process is in the research stage and is not yet commercialized, although a few studies on the
process were conducted from the 1970s to the 1990s.

CATALYTIC STEAM GASIFICATION
▪ Catalytic steam gasification is considered to be more energy‐efficient than steam‐oxygen gasification.
▪ In this process, gasification and methanation occur in the same reactor in the presence of a catalyst.
▪ The energy required for the gasification reaction is supplied by the exothermic methanation reaction.
▪ CH4 is separated from CO2 and syngas (CO and H2); the syngas is then recycled to the gasifier.
▪ The catalytic reaction can take place at a lower temperature (typically 650°–750° C).
▪ The process was initially developed by Exxon in the 1970s using potassium carbonate (K2CO3) as a catalyst, but the
process was not commercialized.

ADVANTAGES OF CATALYTIC STEAM GASIFICATION
➢ They do not require air separation unit; hence, there is less energy penalty for the process.
➢ Furthermore, the costs are lower, as the gasification and methanation occur at a lower temperature.
The disadvantages of catalytic steam gasification are the separation of catalyst from ash/slag and the loss of
reactivity of the catalyst.

COAL LIQUEFICATION:
➢ Coal liquefaction is a process of converting coal into liquid hydrocarbons: liquid fuels and petrochemicals.
➢ This process is often known as "Coal to X", where X can be many different hydrocarbon-based products.
➢ However, the most common process chain is "Coal to Liquid Fuels" (CTL)
➢ The first approach is known as carbonization and the second is known as liquefication.
➢ The major objective of coal liquification is to produce synthetic oil to supplement the natural resources.
➢ It is an attractive technology because:
• It is well developed and thus could be implemented fairly rapidly.
• There are relatively large quantities of coal reserves.

Specific liquefaction technologies generally fall into two categories:
1. direct (DCL) and
2. indirect liquefaction (ICL) processes.
1. Direct processes are based on approaches such as carbonization, pyrolysis, and hydrogenation.
2. Indirect liquefaction processes generally involve gasification of coal to a mixture of carbon monoxide and hydrogen,
often known as synthesis gas or simply syngas.
DIRECT LIQUEFICATION PROCESS:
One of the main methods of direct conversion of coal to liquids by hydrogenation process is the Bergius process, developed
by Friedrich Bergius in 1913.
There are mainly two stages:
• Single stage (produces distillate via one primary reactor or a train of reactor in series)
• Two stage (produce distillate via two reactors or reactor train in series)
The primary function of the first stage is coal dissolution and is operated either without a catalyst or with only low activity
disposable catalyst.

➢ The heavy oil liquid produced in this way are hydro treated in the second stage with a high activity catalyst to produce
additional distillate.
➢ In this process, dry coal is mixed with heavy oil recycled from the process. A catalyst is typically added to the mixture.
The reaction occurs at between 400 °C (752 °F) to 500 °C (932 °F) and 20 to 70 MPa hydrogen pressure.
➢ Typically, the liquefaction reactors operate at temperatures of up to 450 ° C and pressures up to 200 bar with a 3-phase
slurry of coal, recycle oil and hydrogen.
➢ A major ambition in research is to achieve significant cost savings by reducing the intensity of these conditions in order
to reduce the capital cost.
➢ DCL is distinctly different in operation from the indirect processes. As the coal is not gasified, there is limited
opportunity to remove impurities and the products are related to the original structures in the coal.
➢ There are considerable improvements in efficiency in oil production compared to indirect processes, but there is also
more sensitivity to coal properties.

INDIRECT LIQUEFICATION:
Mainly two steps involved:
➢ The first step is to complete breakdown of coal structure by gasification.
➢ The composition of the gasification product is a mixture of H2 and CO referred as syngas.
➢ Sulphur containing compounds are also removed in this step.
➢ The resulting gasification products are reacted in the presence of a catalyst at relatively low pressure and
temperature.
➢ The synthetic liquid products included paraffin’s, olefin hydrocarbon or alcohol depending on the catalyst
selected and the reaction condition used.
FISCHER – TROPSCH PROCESS:
➢ Indirect route for coal gasification used to form syngas directly from Coal.
➢ The process was first developed by Franz Fischer and Hans Tropsch at the Kaiser-Wilhelm-Institut für
Kohlenforschung in Mülheim an der Ruhr, Germany, in 1925

➢ The gasification island consists of all the supporting process technologies of coal handling & feed preparation, heat
recovery, syngas cleanup and conditioning, water-gas-shift, sulfur recovery, etc.
➢ The clean syngas leaving the gasification island is sent onto the FT synthesis island, where the clean shifted syngas is
converted into primary products of wax, hydrocarbon condensate, tail gas, and reaction water.
➢ The wax is sent on to an upgrading unit for hydrocracking in the presence of hydrogen, where it is chemically split
into smaller molecular weight hydrocarbon liquids.
➢ A hydrogen recovery unit is used to extract the required quantity of hydrogen from the tail gas as shown, or
alternatively from the feed syngas stream.
➢ The reaction products, along with that from the upgrading section, are fractionated into the final products of diesel,
naphtha, and other light ends, depending on the
desired product mix.
➢ The production facility is supported by several utility
plants, including the power train.

Chemistry of Fischer – Tropsch process:
❑ The Fischer-Tropsch process is a catalytic chemical reaction in which carbon monoxide (CO) and hydrogen (H2) in the syngas are
converted into hydrocarbons of various molecular weights:
(2n+1) H2 + n CO → Cn H(2n+2) + n H2O
n is an integer.
Thus, for n=1, the reaction represents the formation of methane, which in most CTL or GTL applications is considered an undesirable
byproduct.
❑ The Fischer-Tropsch process conditions are usually chosen to maximize the formation of higher molecular weight hydrocarbon liquid
fuels which are higher value products. There are other side reactions taking place in the process, among which the water-gas-shift
reaction
CO + H2O → H2 + CO2
❑ Depending on the catalyst, temperature, and type of process employed, hydrocarbons ranging from methane to higher molecular
paraffins and olefins can be obtained.
❑ Small amounts of low molecular weight oxygenates (e.g., alcohol and organic acids) are also formed.

Catalysts:
Catalysts considered for Fischer-Tropsch synthesis are based on transition metals of iron, cobalt, nickel and ruthenium.
Among these catalysts, it is generally known that:
•Nickel (Ni) tends to promote methane formation, as in a methanation process; thus generally it is not desirable.
•Iron (Fe) is relatively low cost and has a higher water-gas-shift activity, and is therefore more suitable for a lower
hydrogen/carbon monoxide ratio (H2/CO) syngas such as those derived from coal gasification. Fe catalysts may be
operated in both high-temperature regime (300-350°C) and low-temperature regime (220-270°C),
•Cobalt (Co) is more active, and generally preferred over ruthenium (Ru) because of the prohibitively high cost of Ru. Co
catalysts are only used in the low-temperature range
•In comparison to iron, Co has much less water-gas-shift activity, and is much more costly.

THE KARRICK PROCESS/ LOW TEMPERATURE CARBONIZATION:
➢ A low-temperature carbonization (LTC) and pyrolysis process of carbonaceous materials.
➢ It also could be used for processing of oil shale, lignite or any carbonaceous materials.
➢ It could be used for a coal liquefaction as also for a semi-coke production.
➢ The process was the work of oil shale technologist Lewis Cass Karrick at the United States Bureau of Mines in the
1920s.
➢ For commercial scale production, a retort about 3 feet (0.91 m) in diameter and 20 feet (6.1 m) high would be used. The
process of carbonization would last about 3 hours.
➢ Superheated steam is injected continuously into the top of a retort filled by coal.
➢ At first, in contact with cool coal, the steam condenses to water acting as a cleaning agent.
➢ While temperature of coal rises, the destructive distillation starts.
➢ Coal is heated at 450 °C (800 °F) to 700 °C (1,300 °F) in the absence of air. The carbonization temperature is lower
compared with 800 °C (1,500 °F) to 1,000 °C (1,800 °F) for producing metallurgic coke.

➢ The lower temperature optimizes the production of coal tars richer in lighter hydrocarbons than normal coal tar, and
therefore it is suitable for processing into fuels.
➢ Resulting water, oil and coal tar, and syngas moves out from retort through outlet valves at the bottom of the retort.
The residue (char or semi-coke) remains in the retort. While the produced liquids are mostly a by-product, the semi-
coke is the main product, a solid and smokeless fuel.
➢ The Karrick LTC process generates no carbon dioxide, but it does produce a significant amount of carbon monoxide.

SOLVENT-REFINED COAL PROCESSES
➢ The process of solvent refining is a flexible conversion process whereby solid or liquid products can be varied
according to the amount of hydrogen consumed.
➢ It is also known as Pott-Broche process which was commercially important between 1938 and 1944.
➢ Extraction took place in a tetralin and cresol oil solvent mixture.
➢ The Solvent Refined Coal liquefaction process referred to as SRC-II is a thermal liquefaction process.
➢ It is an outgrowth of an earlier Solvent Refined Coal process tested by Gulf Oil in the 1960s.
➢ The earlier process, known as SRC-I, was aimed at boiler fuel production of an ashless low-sulfur solid fuel. In
contrast, the SRC-II is geared to the production of synthetic liquid fuels.
➢ Typical reactor conditions are 870 °F, 1,500–2,500 psig, and 15–45 minutes with no catalyst.

SIGNIFICANCE OF COAL LIQUIFICATION:
➢ Coal liquification can significantly improve national and economy security by lessening dependence on foreign oil and
substituting plentiful, more affordable coal.
➢ Can be used in current engine leading to reduction in all regulated emission.
➢ Provide a fuel platform for the development of new generation compression ignition engine ideal hydrocarbon fuel for
fuel cells.

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