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Production Of Methanol From Natural Gas



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Production Of Methanol From Natural Gas



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Methanol

Methanol is an Alcohol whose chemical formula can be written as CH3OH. It is a clear, colourless liquid with a mild odour, and dissolves readily in most common organic solvents.
Methanol is one of the largest volume chemicals produced, with a world wide annual
production of about 13 million tons.

Methanol was first obtained commercially some 150 years ago
by the destructive distillation of wood. Today it is produced
mainly from the steam reforming of natural gas via a synthesis
gas intermediate. Methanol can and is , however also being
produced from such alternative feed stocks as coal and residual
fuel oil.

Methanol has been traditionally used as a chemical intermediate
for the production of formaldehyde, solvents, methyl
derivatives(chemical groups containing CH3) and increasingly acetic acid. Recently methanol has gained importance as a clean burning fuel and fuel additive in such diverse uses as a
boiler fuel for NOx control , as an octane booster for gasoline by direct blending or as a methyl tertiary butyl ether derivative and for fuel cell application .
1.1 Physical Properties.-
Methanol (CH3OH) is an alcohol fuel. Methanol is the simplest alcohol, containing one carbon atom. It is a colorless, tasteless liquid with a very faint odor and is commonly known as "wood
alcohol."As engine fuels, ethanol and methanol have similar chemical and physical
characteristics. Methanol is methane with one hydrogen molecule replaced by a hydroxyl
radical (OH).

Physical Properties

Molecular weight 32.04
Boiling point 64.7°C
Vapor pressure 97 Torr at 20°C
Formula CH3OH
Freezing point -97.68°C
Refractive index 1.3284 at 20°C
Density 0.7913 g/mL (6.603 lb/gal) at 20°C
0.7866 g/mL (6.564 lb/gal) at 25°C

has gained importance as a clean burning fuel and fuel additive in such diverse uses as a
boiler fuel for NOx control , as an octane booster for gasoline by

d with a very faint odor and is commonly known as "wood
alcohol."As engine fuels, ethanol and methanol have similar chemical and physical

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Production Of Methanol From Natural Gas



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Production Of Methanol From Natural Gas



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4.1 Methanol Manufacturing Process
The Methanol Industry in Trinidad began with the construction of a 1,200 MT state-owned

the industry has expanded to include four larger plants with an annual production capability
close to 3 million MT of methanol.
At the MHTL Point Lisas Methanol Complex, methanol is made using the ICI Low Pressure
Methanol Synthesis Process. The two main raw materials used are natural gas (96% methane)
received from the National Gas Company (NGC) to provide the carbon and hydrogen
components and water from the Water and Sewerage Authority (WASA) to provide the oxygen
component. These raw materials undergo a series of chemical reactions to produce crude
methanol which is then purified to yield refined methanol, having a purity exceeding 99.9%.
The plants operate continuously 24 hours a day in a production process that can be divided
into four main stages: Feed Purification, Reforming, Methanol Synthesis and Methanol
Purification as shown in the flow sheet below:



STEP1 FEED PURIFICATION


The two main feed stocks, natural gas and water, both require purification before use.
Natural Gas contains low levels of sulphur compounds and undergo a desulphurization
process to reduce, the sulphur to levels of less than one part per million. Impurities in the water
are reduced to undetectable or parts per billion levels before being converted to steam and
added to the process. If not removed, these impurities can result in reduced heat efficiency
and significant damage to major pieces of equipment.


into four main stages: Feed Purification, Reforming, Methanol Synthesis and Methanol
Purification as shown in the flow sheet below:

process to reduce, the sulphur to levels of less than one part per million. Impurities in the water
added to the process. If not removed, these impurities can result in reduced heat efficiency
and significant damage to major pieces of equipment.

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Production Of Methanol From Natural Gas



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0.13% A1 = 3% A7

A1 = 2307.69% A7 (
Putting Eq (2) in (1),

535.15% A7 = 22% A7 + 201.235
513.15% A7 = 201.23



H2 in A7 = 29.41 K.Mol /hr CO in A7 = 5.09 K.Mol /hr CO2 in A7 = 3.52 K.Mol /hr N2 in A7 = 1.17 K.Mol /hr
So Eq(2) becomes,




H2 in A1 = 693.93 K.Mol /hr CO in A1 = 124.70 K.Mol /hr CO2 in A1 = 85.15 K.Mol /hr

N2 in A1 = 1.176 K.Mol /hr



Now suppose, 50% conversion of CO & CO2 per pass
50% * {( 124.70 + 13% * A6 ) + ( 85.15 + 9% * A6)} = 195.0
50% * {( 209.86 + 22% * A6 )} = 195.0
209.86 + 22% * A6 = 390.03
22% * A6 = 180.17

So,
H2 in A6 = 614.23 K.Mol /hr CO in A6 = 106.46 K.Mol /hr CO2 in A6 = 73.70 K.Mol /hr N2 in A6 = 24.56 K.Mol /hr



A= = A1 + A6

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Production Of Methanol From Natural Gas



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A5 = A6 + A7





A3 = A4 + A5







D2 A1 = 904.96 K.Mol /hr
H2 76.68% Mol % H2 57.42% By vol CO 13.78% Mol % CO 10.32% By vol CO2 9.41% Mol % CO2 7.04% By vol N2 0.13% Mol % N2 0.10% By vol W1 H2O 25.11% By vol H2O 100%


D2 = W1 + A1 D2 = W1 + 904.96 (


25.11% * D2 = W1 (
Putting (4) in (3),
D2 = 25.11% * D2 + 904.96 74.89% * D2 = 904.96


H2 in D2 = 693.86 K.Mol /hr CO in D2 = 124.70 K.Mol /hr CO2 in D2 = 85.07 K.Mol /hr N2 in D2 = 1.18 K.Mol /hr H2O in D2 = 303.4 K.Mol /hr
Now putting value of D2 in Eq(4) , we get,






Separator

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