XThermal Technology & Case Studies

XThermal Technology

•          Revolutionary inorganic superconductive heat transfer medium

•          Vacuum sealed into various types of vessels and materials

•          Forms a thermal superconducting component known as XThermal

•          Uniform temperature distribution

•          Passive thermal transfer component

•          Long life span only limited to housing material

•          Non Radioactive, non toxic (equivalent to the radioactivity of wood)

α= 1.4×10^-1 Bq/g β= 1.7×10^-1 Bq/q

Heat Pipe vs. XThermal

Heat Pipe XThermal
Heat Transfer Mechanim Transfers heat via phase change

Pressure build up from thermal runaway

No phase change

Low internal tube pressure

Structure Evaporation/condensation process requires special wick structure No wick structure
Heat Transfer Medium Liquid medium – water, methanol, etc.

Medium volume up to 1/10 of internal tube volume

Inorganic compound medium

Medium volume is 1/400,000 of internal tube volume

Temperature Limitations
  • Narrow operation temperature range
  • Fail when operation temperature exceeds limit
Wide operating temperature range

Will not fail as long as housing    material stays effective

Temperature Distribution Temperature variation along the tube

Heat transfer terminate at cold load – Length limitation

Uniform temperature distribution along length of tube

XThermal superconductivity has no length limitation

Petrochemical/Oil Industry
XThermal Air Preheater Comparison

Air Preheater Advantages Disadvantages
XThermal Air Preheater

  • Simple structure
  • Corrosive free
  • Minimal leakage
  • Minimal maintenance
  • Extremely low maintenance cost
  • Passive system
  • No moving parts
  • Good material compatibility
Slightly larger in volume when compared to rotary type
Rotary Type Air Preheater

  • Smaller in unit size
  • High material requirement
  • High Leakage
  • Severe Corrosion
  • Flammable
  • Moving parts
Heat Pipe Air Preheater

  • Smaller in unit size
  • Low material requirement
  • Large structure
  • Toxic heat transfer medium
  • Low corrosion resistance
  • High maintenance
  • Low heat exchange rate
  • Leakage

Petrochemical/Oil Industry
Air Preheater Case Study

Petrochemical/Oil Industry
Air Preheater Case Study – Features

•          Exceptional compatibility between heat transfer medium and housing material.  (ND Steel and Carbon Steel)

•          Long life span. The operating life span of the component is limited to the housing material.

•          Each XThermal component operates independently. Defects on one or more of the components will not hinder the operation of the air preheater.

•          In each of the cases provided, there is more heat transferred (Btu/hr) in the XThermal Air Preheater than the Ljungstrom.

•          In each of the cases provided, the pressure drop (in H2O) is lower in the XThermal Air Preheater. In each of the cases provided, the XThermal Air Preheater is able to maintain the component metal surface temperature above the critical temperature as stated in the Foster Wheeler report.

•          Ceramic-fiber cord seals in XThermal Air Preheater guarantees a leakage of 0.5% or less.

•          Compared with the 12% leakage in a Ljungstrom, it would result in 24 times less leakage

•          Max. surface temperature of the XThermal tube in mass production 350°C (662°F)

•          Minimal leakage prevents de-rating of boiler

•          Minimal leakage resulting in maximum and consistent boiler efficiency as opposed to the Ljungstrom, which gradually decreases in efficiency due to the increasing leakage rate over time.

•          Performance of XThermal Air Preheater is actually greater than that of the Ljungstrom.

•          The flue gas outlet temperature appears lower with Ljungstrom due to the mixing of air (air leakage) and gas in the unit and not a result of more heat drawn.

•          The leakage also causes the cold spots within the unit and thus, contributes to the corrosion.

•          The entire system has no moving parts.  Hence the operation is maintenance free.  The XThermal component housing is 1.5” diameter carbon steel tubes, and the fin material is 08AL.(ASTM SA 1010) . Flue gas contains an amount of soot which could foul the heating surface and affect the heat transfer capability after a period of operation.  To ensure the cleanliness of the heat transfer surface, the components adopt a nearly horizontal position.

•          The tilted position of the components is able to accomplish partial cleaning by gravity

•          The surface temperature is maintained higher than the critical corrosion temperature

•          Therefore, the particles on the surface are mostly dry ash which is easy to clean

•          A soot blower is installed on the top and an opening is provided at the bottom for the cleaning.

•          Air Preheater is able to expand its capacity through replacing tubes with greater heat transfer area

•          This design fully considers the effects of flue gas and air flow rates.  Proper flow rates and resistance are used to achieve current fan resistance and high heat transfer efficiency.

•          To prevent the surface temperature from dropping below the acid dew point temperature and causing corrosion, fin pitches were adjusted to control the surface temperature.

•          Under low load conditions, the flue gas outlet temperature and component surface temperature are below the acid dew point temperature.

•          Optimal air bypass was adopted as a solution to maintain component surface temperature above the critical temperature of 260˚F.

See the following temperature profile graphs:

Petrochemical/Oil Industry
Air Preheater Case Study – Ceramic Fiber-Cord Seal (Optional)

Petrochemical/Oil Industry
Air Preheater Case Study – Return on Investment (ROI)

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