This large area of chemistry
addresses the removal of various forms of sulphur from produced
hydrocarbons. The areas of petroleum and petrochemicals are
required to meet lower specifications for hydrogen sulphide (H2S)
emissions and in sales gases and liquids. Further complicating
these requirements are shrinking budgets which lowers available capital
Chemistry is the answer to
these restrictions on sales criteria and budgets.
How can this be?
With chemistry, the removal
of material is based on production. For example, when production
is shut down or is interrupted for one reason or another, no chemical is
being used since production = zero, and cost = zero. With a
capital expense, the business is paying for the material IF PRODUCTION
IS OR IS NOT OCCURRING. When production = 0, cost = high $$.
Chemical treatment also lowers available Iron Sulphide which can be
spontaneously combustible when exposed to air.
In a perfect world,
industrial plants and treating systems are not producing in times of
scheduled maintenance. However, unscheduled shutdowns are usually
not the norm.
Many available chemical
treatment strategies exist:
1) H2S Scavenging
2) Combined H2S
and CO2 removal
3) Elemental Sulphur
Hydrogen Suphide Scavenging
is the selective removal of H2S without removing Carbon
Dioxide (CO2). The general reaction is:
H2S + Scavenger
There are MANY different
types of scavenger that cause precipitation, are corrosion inhibitors,
and vary widely in efficiencies and operate at various pressures.
Most applications are for removing hydrogen sulphide from natural gas
sales streams or liquid in which the sulphur content must be in the range of 0.1 -
5.0 part per million. This is completed without removing Carbon
Dioxide from the system which can be Slipstreamed or passed
through the system to accompany the sales gas.
and CO2 Removal
This chemical process
removes both acid gases simultaneously from the natural gas stream.
When low Hydrogen Sulphide levels (0.1 to 5.0 ppm) and Carbon Dioxide
(<2.0 %) are required for meeting sales specifications.
The general reactions are:
H2S + Scavenger
CO2 + Scavenger
Lowering the levels of these
acid gasses also limits/lowers: corrosion, off-specification gas, injury
to operations personnel.
Removal and recovery is
traditionally accomplished using oxygen and sulphur in the chemical
reaction that creates solid sulphur. Recovered sulphur is then
sold to manufacturers in other chemical industries such as: Battery
manufacturers, drug creation, paints, cleaners, and other areas.
The reaction is as follows:
H2S + 1/2 O2
=> S(s) + H2O
Oxygen from the atmosphere
is injected into a hydrogen sulphide stream in the presence of a
chemical catalyst (usually designed by a metallurgical chemist) to cause
reduction (formation) of solid sulphur at an elevated temperature.
Pure sulphur has a melting temperature of 112.8 Celsius (~235
Fahrenheit), and must be kept above this temperature in order for the
sulphur to remain in a liquid state.
A flexible solution
approached with common sense based on the final system will provide the
maximum uptime. Be concerned of vendors who want to sell a generic
system without examining all of the facts. Ensure that the company
employs licensed professional chemists for your chemical solutions.
Would you want a non-licensed mechanic fixing your car?
Eugene for more information.