Problem
The largest U.S.-based independent oil and gas producer and one
of the largest independent processors of natural gas and natural
gas liquids in North America was in search of new technologies to
maintain the pollution control efficiency at their natural gas
treatment facility.
In typical gas plants, the well head natural gas needs to be
treated to remove water, CO2, any sulfur compounds and heavy
hydrocarbons before it is sent to the pipeline. The acid gases
formed by CO2 and H2S are normally removed by amine adsorption. The
amine must then be stripped of these acid gases in order to be
reused. The amine stripper off gas (tail gas) needs to be treated
before discharge to atmosphere to remove residual hydrocarbons and
meet EPA regulations.
Action
Gas and oil plants have historically used direct-fired thermal
oxidizers with no heat recovery for tail gas treatment. The
existing thermal oxidizer at this facility was using a considerable
amount of auxiliary fuel to maintain temperatures of 1,500°F,
ensuring all the organics were combusted but costing them a
significant amount of money in operating costs. Dedicated to
finding a less expensive means of regulatory compliance, the oil
and gas producer challenged several air pollution control
manufacturers to provide a system that was not only effective, but
also energy efficient.
When Anguil was approached to address the air pollution control
needs at this facility, careful measures were taken to assure the
proper equipment selection.
Solution
After much consideration, Anguil offered their Model 75
(7,500SCFM) Regenerative Thermal Oxidizer (RTO) with heat recovery
for efficient and effective operation. Anguil was selected because
of their unique approach toward air pollution control and energy
conservation.
With the Anguil two-bed RTO, the contaminated process gas is
pre-heated as it passes through beds of ceramic media located in
the energy recovery chambers. The process gas moves from the
pre-heat chamber toward the combustion chamber, where the Volatile
Organic Compounds (VOCs) are oxidized, releasing energy into the
second energy recovery chamber before going to atmosphere. A
diverter valve switches the process gas direction so both energy
recovery beds are fully utilized, thereby reducing any auxiliary
fuel requirement. This system is designed for heat recovery of 85%
and is self-sustaining, requiring little auxiliary fuel use. This
energy-efficient design offers significantly lower operating costs
in comparison to other emission treatment methods.
The RTO is designed to prevent corrosion by the acid gases and to
handle the high organic loading with low oxygen levels. The gas at
this facility is "sweet" and does not contain any H2S but
precautions were taken to prevent carbonic acid attack due to the
CO2.. In addition, Anguil provided a Class 1, Division 2,
Group D control package. Heated, fresh air was also introduced into
the system, providing supplemental oxygen without condensing
moisture in the process stream. Anguil's application specific
engineering was an important factor in the success of this
project.
The Anguil RTO is achieving 99% DRE (Destruction Rate
Efficiency) and is expected to save the customer $500,000 per year
in natural gas cost over the direct-fired thermal oxidizer.
Anguil's equipment, detailed system design, installation and
startup has exceeded the customer's expectations of efficiency and
affordability.