LISST-Infinite installed next to a draft tube.
Sequoia’s LISST-Infinite instrument is made to protect turbines by sounding alarms so that plant operators may decide to shut down power production and save turbines from abrasive damage.
The instrument system consists of a mechanism to deliver a stream from the water that is powering the turbine. This stream passes through the instrument housing. A laser diffraction (LD) system in the LISST-Infinite measures the amount of sediment in water. The measured total concentration is presented in 3 size classes: harmless fines (<75 microns), medium (75-200 microns), and harmful coarse grains (>200 microns). Data are sent to computers for display (figure below). Display software provided with the LISST-Infinite has the capacity to generate audible alarms based on operator-set thresholds.
The LISST-Infinite is superior to turbidity, acoustics, or Coriolis effect sensors because those sensor types can be ‘fooled’ by harmless fine particles, setting off false alarms. LISST-Infinite alarms will sound only when dangerous levels of harmful coarse particles are exceeded. Alarm thresholds are set by the user. Upto 5 instruments in a facility can be monitored by the software. The chart below can be displayed on multiple work stations on a network.
[updated 17April 2017]
This strip chart displays 2-month history of concentrations: total (bottom), fines (second from bottom), medium (second from top) and coarse grains (top). Note: high concentrations of fine and medium grains in last 2 weeks of graphs, even though concentrations of harmful coarse particles were low, In such situation, turbidity sensors would set off false alarms. LISST-Infinite would see only a small concentration of coarse particles, and not set off alarms.