Carbon Burn-Out Frequently Asked Questions
- How much energy
can I expect to recover using the Carbon Burn-Out process?
percentage of the coal used in utility boilers does not combust. This non-combusted material is primarily in the form of
carbon and is essentially unused or wasted energy. Unburned carbon is collected with the fly ash and follows
the fly ash either to beneficial use or landfill. The energy value of the unburned carbon is therefore wasted
contributing to the inefficiency of the electricity producing
energy in the form of unburned carbon is the fuel for the Carbon
Burn-Out process. The
CBO process tailors the combustion conditions to recover the energy
(unburned carbon) in the fly ash. This recovered heat is returned to the electricity making
process in the form of hot water.
amount of energy recovered by the Carbon Burn-Out process is
dependent on the carbon content and quantity of the fly ash. In any case, returning the heat to the electricity making
process increases the electricity making efficiency by a
- How large is a
Carbon Burn-Out plant?
Carbon Burn-Out facility typically uses approximately 7000 square
feet of space. Most generating stations can easily accommodate a
CBO facility. In most
utility operations space is a premium. Landfill operations normally consume several square miles
of land area. The CBO process is designed to drastically reduce
the need for space intensive landfill operations thereby
conserving precious natural resources.
- What range of
carbon content can be used with the Carbon Burn-Out process?
Burn-Out can accommodate carbon contents as high as 90% and as low
as 8%. A
minimum of 8% carbon is typically needed for the process to work solely
with the fuel value of the fly ash. For ash streams lower than 8% support fuel may be needed.
- Can the Carbon
Burn-Out process be used for bottom ash?
Carbon Burn-Out is specifically designed for use on fly ash.
- Will the CBO
process allow for 100% of my fly ash stream to become marketable?
using the CBO process are reporting that virtually 100% of the fly
ash produced at the generating station has been placed in the
marketplace. In fact,
several of our customers have indicated demand exceeding the fly
ash producing capacity of the generating station.
- Does CBO fly ash
meet specification for cement replacement use?
produced fly ash meets or exceeds ASTM Class F specifications.
- Has CBO fly ash
gained market acceptance as a Class F ash?
markets where CBO fly ash is available, our customers have
reported that CBO fly ash is the material of choice for use as a
replacement for Portland cement. CBO processed fly ash gives Ready mix operators the
benefits of a consistently produced fly ash allowing improved
quality and performance.
- Can CBO handle moisture treated (conditioned) fly?
In many instances utilities add moisture to the fly ash to enhance handling properties prior to fly ash transportation and disposal. The CBO process was originally designed to use dry fly ash as the feed. Therefore, the CBO process eliminates the need for fly ash conditioning.
However, for instances where there is a conditioned ash system in place and it is not desirable to convert to dry fly ash collection, or if a powerplant desires to reduce the volume of fly ash in the landfill, the CBO could process the conditioned fly ash using PMI’s patented design for processing reclaimed landfill ash in the CBO
- How long does it
take to build a Carbon Burn-Out facility?
of a CBO facility will take approximately 12 to 18 months. Construction
- Will a Carbon
Burn-Out plant accommodate changes in Carbon content? For
example if I add Low NOx burners, I can reasonably expect a carbon
to increase in the ash. What impact will this have on the
of the Carbon Burn-Out System is critical to the success of the
ash treatment program.
size of the Carbon Burn-Out facility is governed by the amount of
carbon combusted. For example a CBO system processing 100,000 tons
per year fly ash containing 16% carbon is roughly the same size as
a Carbon Burn-Out unit processing 200,000 tons per year at 8%
design features of the CBO system allow for variation in carbon
content in the + or – 25% range while maintaining designed
throughput. Once this
“system flex” is exceeded feed rate is adjusted to accommodate
the carbon content change.
- The addition of
NOx treatment has resulted in fly ash with high levels of
ammonia. What happens to the ammonia in the Carbon Burn-out
Carbon Burn-Out process removes all of the ammonia contained in fly
ash. The ammonia is decomposed to nitrogen and water resulting
in ash containing no ammonia residues.
- How many employees
are required to operate a carbon Burn-Out facility?
CBO operations operate 24/7 using two employees per shift.
- What determines
the size of a Carbon Burn-Out facility? What is the largest
and smallest size that can be used?
size of the Carbon Burn-Out system is determined by the amount of
carbon combusted. By the addition of modules the size of the
CBO unit is virtually unlimited. Units are sized to match
the utilities fly ash production and the anticipated demand for
fly ash in the service area.