Industrial Consultancy & Sponsored Research (IC&SR) , IIT Madras

Online Device or Instrument and Methodology to Measure Fly Ash Particulate Optically in Industrial

Technology Category/Market

Technology: Optical opacity monitoring devices;

Industry: Power Plants, Cement Plants, Chemical Industries; Applications: Glass Plants.

Market: The global opacity monitoring market size is projected at a CAGR of 4.6% during period of 2023-2031.

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Problem Statement

  • In the present era, the opacity monitors based on optical extinction & other scattering based instruments are well known in the art for stack dust monitoring.
  • A few prior arts device/techniques have discussed related to conventional dust monitoring instruments which follows new standards & regulations for emission limits, however unable to indicate & measure the true value of emissions due to the interference of the droplets/water aerosol along with other PM emissions including other drawbacks.
  • Hence, there is a need to introduce present invention which mitigates above challenges.

Technology

  • Present invention describes an online device for optically measuring fly ash particulate in industrial stack emissions independent of moisture. Figure 1 depicts the stack & systems for optical measurement, gravimetric sampling, aerosol feeding & data acquisition respectively.
  • Said online device comprises:

  • Further, the depolarization of horizontally polarized incident light observed and quantified for fly ash & water aerosol complete depolarization was observed for fly ash at the 170◦ back-scatter angle, while water droplets retained the incident state.

Key Features/Value Proposition

Technical Perspective:

  • The optical device comprises 16 apertures for detection and 2 apertures for laser to pass through the aerosol medium & then to light trap.
  • There is a component of IRIS for receiving the beam going towards the measurement section with an aperture of diameter 0.5 mm to reduce intensity variations.
  • Further condensing lens (f = 12 mm) for collecting the scattered signal that passes through the polarizer and coupled to a photo multiplier tube (PMT) using the optical fiber.
  • The optical fiber coupling the scattered signal to the PMT was connected to a Wave Runner 6100A oscilloscope for sampling the scattered signal from the particles at 1 MHz per channel & the amplitude was averaged over the duration of pulse (1s) to reduce the effect of random noise. (Refer Fig. 2)
  • The measurements were conducted for 1 MHz, 10 MHz & 25 MHz sampling rates & an acceptable signal to noise ratio (SNR) obtained above 1 MHz sampling rate. (Refer Fig. 3)
  • The photo multiplier tube (PMT) output was averaged over the entire signal pulse above the threshold where the threshold defined as µ + 3σ of the reference signal recorded with the flow without the water aerosol.

Industrial Perspective:

  • Cost-effective & echo-friendly device & applicable for low dust loading applications.
Questions about this Technology?

Contact for Licensing

Research Lab

Prof. Satyanarayanan Seshadri

Department of Applied Mechanics & Biomedical Engineering

Intellectual Property

  • IITM IDF Ref.:1807
  • Patent No.389506
  • PCT Application No. PCT/IN2020/050035

Technology Readiness Level

TRL-4/5

Proof of Concept, Tested & Validated

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