Carbon Burn-Out Frequently Asked Questions

• How much energy can I expect to recover using the Carbon Burn-Out process?
• How large is a Carbon Burn-Out plant?
• What range of carbon content can be used wtih the Carbon Burn-Out process?
• Can the Carbon Burn-Out process be used for bottom ash?
• Will the CBO process allow for 100% of my fly ash stream to be marketable?
• Does CBO fly ash meet specification for cement replacement use?
• Has CBO fly ash gained market acceptance as a Class F ash?
• Can CBO handle moisture treated (conditioned) fly ash?
• How long does it take to build a Carbon Burn-Out facility?
• Will a Carbon Burn-Out plant accommodate changes in Carbon content?  For example if I add Low NOx burners, I can reasonably expect carbon to increase in the ash.  What impact will this have on the CBO System?
• 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 process?
• How many employees are required to operate a Carbon Burn-Out facility?
• What determines the size of a Carbon Burn-Out facility?  What is the largest and smallest size that can be used?

• How much energy can I expect to recover using the Carbon Burn-Out process?
  A 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 process.

  Wasted 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.

  The 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 measurable percentage.

• How large is a Carbon Burn-Out plant?
  A 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?
  Carbon 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?
  No, 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?
  Facilities 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?
  CBO produced fly ash meets or exceeds ASTM Class F specifications.

• Has CBO fly ash gained market acceptance as a Class F ash?
  In 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 uses dry fly ash as the feed.  The CBO process eliminates the need for fly ash conditioning.

• How long does it take to build a Carbon Burn-Out facility?
  Construction of a CBO facility will take approximately 12 to 18 months.  Construction Photos

• 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 CBO system?
  Sizing of the Carbon Burn-Out System is critical to the success of the ash treatment program.

  The 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% carbon.

  Certain 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 process?
  The 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?
  Commercial 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?
  The 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.