Sequoia Scientific LISST-Infinite - Instrument
The LISST-Infinite instrument is designed for use in hydro-power plants to monitor sediment concentration and size distribution for turbine protection. The instrument is installed near intakes, or near draft tubes. The turbid water pressure is reduced to 5 PSI or less and then piped or pumped to the LISST-Infinite. A clean water source is provided for automated dilution. The automated dilution enables the LISST-Infinite to measure silt concentrations from ~5 to 30,000 mg/l.
1. On-Line Sediment Monitoring System – LISST-Infinite
The LISST-Infinite is a version of the field proven submersible LISST-100X particle size analyzer. The system combines an automatic dilution system with the laser diffraction particle size analysis to accurately measure size and concentrations as high as 30,000 ppm. The LISST-HYDRO is a version of the LISST-Infinite without the automatic dilution system. Both systems are designed for continuous measurements in hydro power dam environments.
In this application the LISST-Infinite will accept low pressure water (<5 psi) from the sediment source up stream or downstream of the turbine. Water flows through an internal sample cell. A measurement of size distribution and concentration is made. If the concentration exceeds a preset threshold, a sample is captured and then diluted by a factor of 10. This diluted sample is then circulated through the sample cell and another measurement is made. Below is a list of features of this system.
2. LISST-Infinite features
2.1. Concentration and Size Ranges
Detailed particle size and concentration measurements capability. Measurement of sediment concentration in the following size ranges:
- Total Concentration between 0.0019 and 0.381 mm
- Concentration in 32 log-spaced size classes from 0.0019 mm to 0.381 mm
- Concentration of particles greater than 0.2 mm (and up to 0.381 mm)
- Concentration of particles between 0.2 mm and 0.075 mm
- Concentration of particles less than 0.075 mm (and down to 0.0019 mm).
2.2. On-Line Display and Alarms
A fully featured Windows graphical user interface is included to display current sediment conditions and instrument status. Some of the features of this program are:
- Alarm when total ppm exceeds a user selectable threshold with an increasing trend.
- Alarm when coarse sediment (greater than 0.2mm) exceeds user selectable level.
- Display of Total ppm including current value and time history Display of ppm greater than 0.2mm including current value and time history plot.
- Display of current size distribution in 32 size classes
2.3. Mechanical Features
The LISST-Infinite is designed to be used in industrial environments. It is housed in a sealed enclosure to protect it from exposure. Some of the mechanical features are:
- Dimensions: 60cm tall, 71cm wide, and 20cm thick
- Weight: 15 kgs ( Note: these dimensions are subject to change)
- Operating temperature range: 5 to 45 deg C
- Storage: 5 to 45 deg C, less than 80% humidity.
2.4. Electrical Features
The LISST-Infinite is designed to be used with AC power. Some of the electrical features are:
- Power source: 220VAC power supply for generating the 12VDC voltage for system.
- RS232 serial communications at 19,200 baud
3. Additional equipment necessary for the operation of the LISST-Infinite and LISST-HYDRO, but NOT included with the instrument quote.
3.1. Monitoring PC
The sediment monitoring software is included in the price of a LISST-Infinite or a LISST-HYDRO, but no PC is included in the price. If a PC is ordered, it will come with the monitoring software pre-installed and tested with the instrumentation prior to shipping from Sequoia’s facilities.
3.2. Clean Water
The LISST-Infinite and LISST-HYDRO both requires a source of clean filtered water for dilution of high concentration samples. This supply of filtered water is not included in quotes. A clean water system can be quoted, which will include clean water tank, filters and necessary tubes, hoses and pipes for connecting to the instrument. Prior to quoting of the clean water supply, Customer must supply drawings of the intended installation location, incl. location of clean water source, intended mounting location of LISST-Infinite or LISST-HYDRO and drain.
The clean water tank must be mounted 1-2 feet above the instrument itself and in close proximity to a suitable clean water source. The approximate maximum consumption of filtered water is about 0.5 / 1.0 liter per sample (LISST-HYDRO / LISST-Infinite ).
3.3. Water sample acquisition system
The customer must provide a low pressure source of turbid water extracted from either upstream or downstream of the turbine. The pressure of the water stream must be less than 5 psi (0.34 bars) and have a typical flow rate of around 6 liters per minute. Alternatively, Sequoia’s LISST-PUMP can be quoted as part of the instrument package for pumping water to the instrument from the reservoir, siltation chamber or upstream of the intake.
3.4. Cabling from instruments to monitoring PC
No cable for connecting the LISST-Infinite / LISST-HYDRO to the monitoring PC is included in the price for the instrument. To receive a cable quote, customer must provide Sequoia with drawings showing the intended routing of the cables from the instrument location to the control room with the monitoring PC.
4. Customer responsibilities
4.1. Civil Works
The customer will provide suitable civil works for housing of LISST-Infinite near the desired sampling location. The enclosed space must have a source of heat to maintain the temperature around the LISST-Infinite greater than 5 deg C such that water does not freeze inside the instrument. Freezing could damage subsystems. The instrument warranty becomes void if the instrument is subject to freezing temperatures while operating. Sequoia Scientific will provide detailed instrument dimensions, technical specifications of the required space, and can provide support for design if necessary. Customer will be responsible for ensuring that cabling from instrument to monitoring PC’s can be run in a suitable and appropriate manner.
4.2. Instrument Power
The LISST-Infinite will require 220VAC power to power its systems. The customer will provide 2 switched standard wall outlets near the desired mounting location of the LISST-Infinite. The two outlets can share a 15 amp breaker and will be used for powering the LISST-Infinite system and other test equipment during installation.
4.3. Contact Person
Upon ordering, the customer will identify an individual that will be responsible for receiving full training on the operation of the LISST-Infinite and be the primary contact with Sequoia Scientific, Inc personnel and/or its agent.
4.4. Installation Assistance
During installation, customer will provide a person who can immediately assist Sequoia personnel with the installation. Of particular importance is unhindered access to cable trays, pointing out walls that can be used for mounting the LISST-Infinite / LISST-HYDRO and the clean water tank(s), assist with stringing cables, provide permanent and unhindered access to a clean water source for filling the clean water tank(s).
5. Sequoia Scientific Inc. Responsibilities
Sequoia will provide LISST-Infinite/LISST-HYDRO according to the Options selected by the customer as per quotation.
Sequoia (or its agent) will install the LISST sensor at the location agreed upon between Sequoia and customer.
Note that installation charges are *NOT* included in the price for the instrumentation itself. All installation charges are to be quoted separately based on location, expected duration of travel/installation and number of personnel involved.
Sequoia (or its agent) will install the cable quoted by Sequoia, connect the LISST-Infinite to a dedicated PC in the Dam Control Room using the dedicated cabling. Software will be provided for viewing the detailed size distributions and time histories of the concentrations in four size classes on this PC only.
Sequoia (or its agent), will provide detailed on-site training for the customer and customer’s personnel on the operation and maintenance of the sensors.
6. Optional Features
As Sequoia personnel become more familiar with the details of the application, additional optional features can be recommended. An example of such an option is to include a 4-20ma output for Total Concentration and Mean Size that can be connected to existing data monitoring systems.
Three (3) annual service trips by trained Sequoia Scientific technicians or Sequoia’s agent will be required to ensure optimal operation. The cost of this maintenance will be quoted separately based on location. In addition a weekly or bi-weekly servicing (typically ½ hour duration) will be required by trained customer personnel, i.e. check if operating OK, cleaning of windows. Training for weekly / bi-weekly servicing will be provided at time of installation. If weekly / bi-weekly service is not performed correctly and on time, data quality cannot be guaranteed by Sequoia.
The LISST-Infinite/LISST-HYDRO will be warranted against defects in material or workmanship for a period of 24 months from the date of commissioning OR 30 months from the date of shipping from Bellevue, WA, whichever is shorter.
Data are transmitted and displayed in the control room. Alarm levels can be defined by plant operators. These levels can be based on either total sediment concentration, or concentration in a particular size range (e.g. the size bins covering 75-500 microns). When concentration of sediments reaching the turbine crosses this threshold, an visible and audible alarm is sounded on the monitor screen. At this point, plant operators may choose to initiate action such as a plant shutdown. Power production can resume when danger passes, for which an ‘all clear’ is sounded.
For both conditions, advance warnings are displayed, (e.g. “Sediment Concentration will reach danger level in 3 hours”, or that it will “…clear in 2 hours..”). The particle size distribution (PSD) can be viewed by clicking on a data point on the strip chart. The PSD display shows concentration (units: mg/liter) of grains in 32 size classes. Data are archived on PC or network for later viewing on-site or off-site or for report preparation.
Damage to turbines occurs by the scouring action of large grains. Thus, the data requirement is for concentration of the coarser grains. Although no set threshold exists, only grains larger than 200 microns are considered harzardous by some plant operators. In research in progress, it appears that the abrasion potential depends on grain size, velocity, and hardness. The LISST-Infinite provides real-time data on concentration of sediment in 32 size classes, from 2 to 400 microns (for other requirements, please contact us). Operator defined danger thresholds can be built in via the software.
- Auto-dilution system for continued operation in high-concentration environments (concentration in excess of 2,000 mg/l).
- The auto-dilution system consists of a dilution chamber, a mixer pump and a pinch valve system. The pinch valves enable the LISST-Infinite to capture a small sample of turbid water, transfer it to the dilution chamber where it is diluted 10:1, and then recirculated using the mixer pump through the optics system for a second measurement.
- With the dilution, the upper concentration range is extended to about 30,000 mg/l (ppm by mass).