Acetylene
with the chemical symbol C
2H
2 is a hydrocarbon
consisting of two hydrogen atoms and two carbon atoms. Acetylene plants are
large or small sized systems generating pure acetylene, which is used for
various industrial purposes. A combustible gas with a distinctive odor,
acetylene is colorless. Once the gas is compressed, liquefied, mixed or
heated with air, it becomes very explosive. For commercial purposes,
acetylene is produced from several different raw materials depending on the
process applied. The production and handling of this gas in the gas plants
require adequate and special precautions.
Manufacturing Process
There are two processes used to make acetylene:
- Chemical reaction process : Occurs at normal temperatures.
- Thermal cracking process : Occurs at extremely high
temperatures.
Chemical Reaction Process
The chemical reaction between calcium carbide and water lead to generation
of acetylene but during the manufacturing process, a considerable amount of
heat is generated which when not removed can lead to the exploding of the
acetylene gas. The chemical reaction process has several variations in which
either water is added to calcium carbide or the other way round. Both
variations of the process are also called wet processes. This is because the
heat of the reaction is adsorbed by an excess amount of water. There is
another variation known as the dry process, in which a limited amount of
water is used, which then evaporates as it absorbs the heat.
Thermal Cracking Process
Another process of producing acetylene is the thermal cracking process.
This process involves increasing the temperature of various hydrocarbons to
very high levels where their atomic bonds break, or crack and hence known as
thermal cracking process. After the hydrocarbon atoms separates, they can
also be joined to form different materials than the original raw materials.
This thermal cracking process is widely used to convert oil or natural gas
to a variety of chemicals. Like the chemical reaction process, depending on
the raw materials used and the method for raising the temperature, there are
variations of this process as well. Some uses an electric arc to heat the
raw materials, some uses a combustion chamber that burns part of the
hydrocarbons to provide a flame, while others produce acetylene as a
co-product of the steam cracking process used to make ethylene.
Storage and Handling of Acetylene
Proper care must be taken in the storing and handling of acetylene because
of the highly explosive nature of the gas. The pressure is kept very low
when the gas is transported through pipelines. Usually the length of the
pipeline is very short. In most gas production operations, the acetylene is
transported only as far as an adjacent plant, or as they say in the chemical
processing business "over the fence". There are special storage
cylinders to store acetylene when it is used in oxy-acetylene welding and
metal cutting operations.
Acetylene Gas Plant Layout
Building a acetylene gas plant requires special precautions and a proper
plant lay out which we are mentioning below:
- As a rule, there must be a gap of atleast 15 m all around the
acetylene plant from any other building. This gap must be minimum 9 m
from any slurry pit.
- Even the acetylene gas storage should be constructed with a 12 m.
safety zone all around.
- If there is an oxygen plant in the vicinity a minimum distance of 90
m must be maintained.
- All manufacturers must provide separately all non-flame and explosion
proof switches, in an area away from the acetylene plant building.
- For the construction purposes of the acetylene plant building no
flammable material should be used.
- The acetylene plant building should be well-ventilated. There should
be ventilators on the roof as well as ground level, and they should be
non-corrosive, galvanized. No rain water should enter the acetylene
plant building and hence covers should be provided on the ventilators.
- All electrical wiring should be of low voltage in the premises.
Electrical lines should also not cross any pipe carrying water or steam
or acetylene.
- There is no need of a gas holder
- Automatic controls
- Residue kept in suspension
- Easy to operate and maintain
- Automatic thermostatic water inlet residue outlet
- There is no vent of acetylene from the tank to the atmosphere
Uses of Acetylene
One of the main purpose of acetylene is that it can be used as fuel gas. Of
all the fuel gases, acetylene produces the hottest flame (3200°C) when
burned with oxygen. It provides high productivity, low oxygen consumption
and safe use within confined spaces. The high level reactivity property of
acetylene makes it a very useful fuel gas for:
- Cutting : It offers higher cutting speed, better cut quality,
and reduced oxygen use compared to other fuel gases.
- Welding : Acetylene is used in welding and it is economical
to electric welding. This is also a good alternative for remote areas
that do not have a reliable electrical supply. Acetylene is the only
fuel gas that creates a flame which is hot enough to weld metal like
steel.
- Heat treatment : It is used for flame hardening of steel or
for large components that do not fit in a furnace.
- Coating : Acetylene is also used for flame spraying. It is
used to spray flame with wires or powder non-stick mold coatings in
metal casting or onto metals and ceramics.
- Acetylene gas is used as a raw material for the production of various
organic chemicals.
- Some commercially useful acetylene compounds is used in certain
dry-cell batteries, and acetylenic alcohols, which are used in vitamins
synthesis.
Industries that use
Acetylene:
Acetylene's use in cutting, welding, heat treatment and coating, makes it a
very useful gas to be used in a wide range of industries:
- General Fabrication and Ship building
- Laboratories and Research
- Glass
- Iron and Steel and Non-ferrous metals
Equipment used in
Acetylene Gas Plants
- Acetylene Generator
- Low Pressure Drier/Condenser
- Purifier
- Acetylene Compressor
- Ammonia scrubber
- High Pressure Drier
- Filling Manifolds
- Acetone Pump
Buyer's Guide
Acetylene Specifications to consider for purchasing acetylene plants are as
follows:
- Capacity
- Purity
- Power requirement
- Carbide size
- Power supply
- Operating pressure
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- Filling pressure
- Starting time
- Assembly height
- Weight about
- Cylinder filling per batch
- Carbide requirements
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Acetylene
Plant
Acetylene
Plant