Zolo Technologies’ Approach to TDLAS

Key Features of Zolo TDLAS

  • Provides real-time, in-situ, simultaneous measurement of temperature, O2, CO and H2O directly in the furnace.
  • Path averaged measurement over the line-of-site of the laser provides better representation of flue gas concentration than a single point measurement from traditional sensors.
  • Multiple paths can provide spatial profiles of temperature and O2, CO and H2O much better than a single path TDLAS system.
  • Measurement data transferred via OPC or Modbus to control system or historian
  • Designed for the ultra-harsh combustion environment:
    • Non-intrusive: there is nothing inside the furnace to corrode, erode, plug up (such as sampling nozzles) or maintain.
    • Fiber-coupled architecture: All of the key electronic components are located away from the furnace. For example, the lasers and data processor are located in the environmentally-controlled room or Class 1, Division 2 classified control rack, if necessary.
    • Auto-alignment: Each SensAlign head has an automatic alignment capability to maintain ideal laser alignment as the furnace  changes (such as during load changes).
  • No field calibration is required: Once the ZoloSCAN is commissioned there is no requirement to periodically calibrate the system using calibration gases as with extractive gas sensors.
  • Low maintenance requirements:
    • The ZoloSCAN is designed for low maintenance. Primary maintenance is cleaning windows and with natural gas fired applications the frequency of window cleaning is low (i.e. no ash).
    • All maintenance and repair can be performed while the furnace is operating.
    • No periodic calibration requirements.
  • Central control rack architecture holds all of the lasers and signal processing. This permits a high number of measurement paths (up to 30) from a single control rack. A single ZoloSCAN system can service multiple adjacent furnaces.

What is unique about Zolo’s approach to TDLAS?

All TDLAS systems use the principle of spectral light absorption. However, the main differences between the ZoloSCAN and other TDLAS systems are the following:

  • Multiple Constituents: ZoloSCAN uses a multiplexer which combines several laser wavelengths into a single beam which can be transmitted via fiber optics to the furnace. This allows the ZoloSCAN to measure multiple constituents simultaneously (Temp, H2O, O2 and CO) with one set of lasers and one laser beam. Other TDLAS can only measure one species at a time via separate laser beams. For example, with other TDLAS systems two separate sensors and two separate paths would be required to measure both O2 and CO. Furthermore, measurement of O2 + CO over 15 paths would require 30 individual sensors (and 60 furnace penetrations). The Zolo system can monitor up to 30 individual paths from a single control system with only half of the furnace penetrations.
  • Fiber Coupled: The ZoloSCAN is fiber coupled which means that the lasers are all housed in a central control rack (typically in the relay room or away from the furnace). The laser signals are sent to the furnace via fiber optics. This allows the ZoloSCAN to measure multiple paths yielding a 2-D profile of each constituent. This architecture provides protection of the critical electrons from the harsh furnace environment. Other TDLAS sensors mount the lasers directly on the wall of the furnace (often requiring cooling), measure only a single path and therefore do not provide profiles.
  • Auto-alignment: ZoloSCAN has an automatic alignment mechanism to keep the laser in alignment as the boiler changes.
  • Port Rodder: ZoloBOSS has an automatic port rodder system that keeps the furnace penetrations clear of slag (on coal-fired applications).
  • Collimated beam: The ZoloSCAN collimated laser beam (compared to a divergent beam) transmits more concentrated power across the furnace thereby permitting measurements in higher dust environments such as coal-fired furnaces and electric arc steel furnaces.
  • Reliable: ZoloSCAN uses telecom-grade lasers which are robust and designed for 100,000 hours of life.