ANDRITZ TMP reboiler

ANDRITZ Heat Recovery Unit (HRU) for TMP plants

The mechanical action of a TMP refiner generates considerable heat.  In times when energy costs were low, this heat was released to the atmosphere.  Today, heat recovery is vital to the energy economics in a mechanical or semi-mechanical pulp mill.  ANDRITZ provides technology for heat recovery from the refiners that also recovers turpentine.

In mechanical pulping, wood chips are processed under elevated temperature and pressure in refining equipment that consumes a significant amount of electrical power and also generates a significant amount of mechanical energy. Approximately 70–80% of the total energy input into a refiner is released in the form of water vapor. Some mills still "waste" this energy by condensing the released vapor with cooling water. However, this energy can be captured and used to generate fresh steam in an ANDRITZ Heat Recovery Unit (HRU).

Special design for TMP vapors

The vapor generated by TMP refiners can be difficult to handle because it is heavily contaminated with fiber and contains large amounts of Non-Condensable Gas (NCG) which is mostly the air in the wood chips. The unique design of the reboiler in the ANDRITZ HRU enables the system to handle difficult TMP vapor without plugging:

  • Pressurized TMP systems generate low pressure steam
  • Atmospheric systems generate vacuum steam

With a pressurized refiner, enough energy can be recovered in the HRU to meet the low-pressure steam requirements of the drying system. The HRU also recovers the turpentine released from the process.  This reduces VOC release into the atmosphere while offering excellent economics.


  • Easy to operate
  • Non-plugging, handles difficult TMP vapors
  • Less cooling water required, thermal energy generates steam
  • Recovers turpentine
  • Other contaminants are captured in a much smaller condensate flow

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