Iron Ore Level Measurement Through Grizzly
HAWK’s brand new 80GHz freespace radar, featuring Frequency Modulated Continuous Wave (FMCW) pulse technology is making waves early. We had a customer with an iron ore rail facility fines bin that had not had a successful level measurement solution to prevent overspill and ensure continuous, uninterrupted material flow through the vessel.
As the vessel was for fines, the grizzly bars (cross beams designed to protect the bin from oversize lump material falling in) were very narrow. HAWK selected the brand new S80P, Senator 80GHz Radar specializing in powder applications for the task. The 70mm (2 ¾”) antenna design along with the 80GHz FMCW pulsing creates such a narrow beam angle that the unit easily measured the iron ore through the grizzly without any advanced parametrization or customized setup.
The ore is fed to a train loadout, so continued uptime is critical. The front loader and train loadout operators need to know and trust their control instrumentation is accurate which the Senator S80P Radar is providing.
The Senator Radar is available in 6 different model types covering a wide suite of level applications, from simple liquids to long range solids.
Measuring Continuous Level of Jet Fuel
Jet fuel has dielectric constant of 1.3 and is extremely flammable. Detecting materials have low dielectric constant (dK) always been a challenge for radar technology. The customer also requested to provide the measurement readings in volume (liters) while the horizontal tank is sitting at 2 degree angle.
The customer (a major airline carrier) had tried competitors’ level technology but the units were not operating reliably.
The installation is classed as a hazardous location requiring electronics to be explosion proof. The input requirements are intrinsically safe low voltage.
HAWK Centurion Guided Radar (CGR) is designed to detect materials with dK lower than 1.3. HAWK CGR unit has recently been installed and successfully commissioned on site and is measuring continuous level of jet fuel in a horizontal tank. CGR unit has been reliably and accurately monitoring continuous level and accurately providing readings in volume (liters) as requested.
The HAWK CGR is hazardous rated with IECEx, FM, CSA and ATEX for Gas and Dust explosion.
Lime Kiln Production Control
Quicklime production occurs in huge kilns where high volumes of limestone and other materials are conveyor fed into a refractory brick lined oven and heated to extremely high temperatures (approximately 900◦C / 1650◦F).
After the limestone passes the burners, the final product quicklime is drawn away and cooled. One of the major obstacles for these high temperature vessels lined with refractory bricks is figuring out how to avoid catastrophic overspill and maintain the optimum level of limestone to keep the burners and the process operating as efficiently as possible.
A major limestone producer approached HAWK’s Italian representative, BERTHOLD ITALIA S.r.l. for level control in their kilns after testing many competitors’ technologies and were unable to get a reliable result.
BERTHOLD ITALIA S.r.l suggested the HAWK Gen 3 Microwave system to control the limestone level. The Microwave was installed behind a high temperature ceramic application seal and the world leading signal receiving circuitry had no problem detecting the incoming signals despite the presence of ceramic, firebricks and limestone dust. The ceramic protects the electronics from any wear and makes maintenance and setup perfectly safe without the need to shut down the kiln.
HAWK’s Microwave level switches are specially designed to avoid false trips where other competitors technology cannot handle signal loss, build up and material curtains.
Remote Microwave System with Ceramic Windows & Weldments plus connection cable.
- 1 x GSASUS
- 1 x GMSB101XX
- 1 x GMRR101XX
- 2 x MA16
- 2 x CA-GMR30M
Controlling Gravity Thickeners
The customer had a major problem controlling his gravity thickeners at a waste water treatment plant. Gravity thickeners at waste water treatment plants do not use chemical floccing to settle suspended solids.
Suspended solids concentrations can change depending on peak and off flows as well as how well the biological system is running in the other part of the plant.
Controlling the underflow density of the bed being pumped to digesters and or filter presses is very important to reduce running costs for the filter presses and extremely important for the optimum performance of the digesters.
By installing low frequency, high powered sonar array transducers, with auto cleaning, we were able to penetrate through the high levels of suspended solids and still provide a reliable bed level for the underflow pump control of the thickener.
Conveyor Transfer Chute
The client was using two approaches for Blocked Chute switches in his conveyor transfer chute. The first technology was the hinged Impact Door that would open when a blocked chute condition developed in the chute and a proximity sensor would indicate that the door had moved. The problem was that buildup of fines material behind the door, sometimes prevented the door from operating if the operator, didn’t hose down the chute on a constant basis. The other problem with the Impact Door, was that after each blocked chute condition, when the door opened, an operator, would have to attend the chute to clean the door jam, so as to shut the door again, to reset the switch.
The second technology used, was the Tilt Switch, higher up in the chute, to provide additional protection, when bridging of wet ore prevented flow through the chute. Bridging generally occurs with wet or damp ore. Overtime, the tilt switch suffered buildup issues around the switch and prevented it from operating, when a blocked chute condition, caused by bridging occurred. Operators needed to hose down the tilt switch on a constant basis.
When mines and port facilities, measure downtime of production in AUD$100,000’s, then a relook at the technology that has been used, is justified.
For both applications we have elected to use the Self-cleaning Acoustic Switch, which provide self-cleaning, by way of the low frequency pressure wave that is produced with each pulse of the transducers. The Acoustic technology, can tolerate both wet and dry ore as they are not reliant on a dielectric constant in the ore too produce a switch point. The transducer diaphragms are made from Titanium and therefore are a wear plate in their own right. The Acoustic Switch system is a fully failsafe switch that can also provide additional pre-maintenance warning on critical chute applications.
The Acoustic Switch system to replace the tilt switch provided more advantages, in that they can tolerate ore flowing through the measuring beam, allowing for the Acoustic Switch to be mounted lower in the chute, providing a faster blocked chute condition signal. This reduced the downtime problem of digging out the chute when the tilt switch did operate.
Each system comprises:
- 1 x GSASUS: Gladiator Remote Amplifier
- 2 x AWRT15Y4XXXC15XAS: 15Khz Titanium face, 15M cable
- 1 x AWRT-JB-01: Junction Box
- 2 x FA4A-4: 4” ANSI Flange
Lime Powder Silos & Lime Slurry Makeup Vessels
The client had intermittent problems with the supplied radar transmitters for the two vessels, measuring Lime Powder in the silo and Lime Slurry in the makeup vessel. The client was using Lime, as a means of correcting the pH of the return process water at a Coal Washery.
Lime powder, was conveyed into the Silo, using lean phase pneumatic air from a delivery truck. Transporting Lime powder through an airline causes friction and will increase the temperature marginally inside the silo. This creates condensation in the top of the silo. Lime is very hydroscopic in nature and the powdered form will take moisture in readily.
Any transducers or probes mounted, in the top of the vessel, will be coated in Lime powder, which will solidify out over time, causing the passive Radar transmitter technology, or high level probe to prematurely fail.
We installed low frequency Acoustic Transducers in the silo and makeup vessel. The self-cleaning Acoustic technology, produces high amplitude pressure waves with each pulse, that prohibits the Lime powder from building up on the operating diaphragm. We used rubber/polyurethane focalizer cones to enhance the cleaning action and to minimise the operating beam angle of the transducers.
The Lime silo, used the more powerful 10Khz transducer, to provide continuous level control even when the Lime is being “blown” into the silo, creating high dust and turbulence levels.
The Lime makeup vessel, was smaller in depth and we supplied a 20Khz transducer, to counter buildup issues and froth/foam floating on the slurry surface. Both instruments are clean of buildup in the focalizer cone and on the diaphragm.
The Sultan Acoustic Transmitter system, comes with a Mine related application selectable menu, to minimise calibration and to simplify the commissioning.
- 1 x AWR234SUXXXX: Remote Sultan Transmitter
- 1 x AWRT10S4XXXC15XX: Remote 10Khz Transducer
- 1 x C10-10-8: Rubber/Polyurethane Cone
- 1 x FA10A-4: Flange 10-00” ANSI
Lime Makeup Vessel:
- 1 x AWR234SUXXXX: Remote Sultan Transmitter
- 1 x AWRT20T4XXXC15XX: Remote 20Khz Transducer
- 1 x C04-8: Rubber/Polyurethane Cone
- 1 x FA4A-4: Flange 4-00” ANSI
Blocked Chute Detection for Brick Making Plant
A well-known brick manufacturer was experiencing blockages in the base of their feed hopper during the production process which ultimately resulted in costly and lengthy plant shutdowns, site hazards and resources re-directed to clear the material.
HAWK engaged with the client to provide a cost effective and reliable means to monitor and control the build-up of material in this situation.
HAWK provided their proven Gladiator Admittance Switch technology for these applications, the remote variant (controller and probe separated) was provided and so the controller could be installed in the local control room cabinet for ease of set up and remote monitoring.
Relay outputs from the amplifier where connected into the clients control wiring so enable the clay feed circuit to drop out of auto on a blockage and restart automatically once the chute was cleared.
1 x AS2200S111TB15XP10 Gladiator Remote Admittance Probe
1 x GSASUS Gladiator Remote Amplifier
1 x CA-GMR50 (50m connection cable)
A Solution to Prevent Mass Flooding in City Centers
Due to the constant flooding of the Flag Square, the City of Rio de Janeiro decided to build five underground reservoirs, known as “big pools”, which together would capture and store rainwater and prevent the overflow of rivers and flooding the streets. However, in March 2016, Flag Square (Praça da Bandeira) was back in the news because the local reservoir overflowed and, again, the streets flooded.
With storage capacity of 18 million litres (19 meters deep and 35 meters diameter), the “big underground pool” was not able to operate as desired. Analysis experts concluded that the lack of reliable information on the level gauge installed in the reservoir contributed to poor performance of the system, preventing the operators from being able to control and properly trigger the drainage pumps. This resulted in an immediate recommendation to replace the existing measuring instruments.
The company hired by the management of Rio Water Foundation Hall of Rio de Janeiro responsible for the project, invited MS Instrumentos (HAWK Partner) to study the problem and offer a reliable solution.
After careful evaluation of the situation, Hawk Measurement Systems’ Sultan AcousticWave level device was recommended as a solution to continuously measure the level of water in the underground pools. The Sultan Acoustic Wave level meter operates on the principle of acoustic waves. Acoustic Wave is different from traditional level products (like ultrasonic and radar). It combines low frequency, high power and adaptive gain technology to measure some of the most difficult level applications (even with foam, dust and vapours present). The Sultan Acoustic Wave works on applications such as solids, liquids, slurries and anti-collision system. The system is self-cleaning so it requires very little maintenance.
MS Instrumentos will perform continuous on-line measurement and support of the level in the reservoir. Also, the outputs from the device will provide the operators information for driving pumps during days of rain, allowing water drainage for the system and preventing floods such that Flag Square has experienced in the past.
Crusher Chute Level Control
This is an application involving the use of a Sultan on a Crushed Rock hopper at a Quarry in Victoria, Australia.
Radar was initially installed on this application to measure a differential change of 1 meter over a 3 meter range from the top of the hopper. As this is a dusty application the Radar has been inconsistent in its operation to the point where it was indicating a full hopper even when the hopper was empty. This meant down time on production based on a false level signal from the radar unit typically due to dust and other false signals & readings.
HAWK Installed and commissioned a new HAWK Sultan system with remote electronics. The result was excellent with commissioning being completed in a very short period of time.
Feedback during our follow up to the customer on site this system has not stopped production since its installation at all. The customer is extremely happy. As a result of this we have now supplied on 5 new additional Sultans with potential for 7 more on their storage bins. The customer has 20 sites around Australia and this Quarry in Victoria is one of their most important sites.
- 1 x AWRT15T4XXXC15XX Remote 10Khz Transducer
- 1 x AWR234SUXXXX Remote Sultan Transmitter
- 1 x FA8A-4 Mounting Flange 8-00” ANSI acoustically isolated flange
- 1 x C08-15-5 8” polyurethane cone for 15kHz
Protecting Apron Feeders
The client used the HAWK low frequency acoustic transmitter to monitor the 40 m (130 ft) stockpile successfully. The transmitter automatically compensated for large lump ore to fines. The acoustic transmitter was not affected by wind, dust or rain.
The problem was when the stockpile was wet the fines would not flow and a “rathole” all the way to the apron feeder may appear. This produced high wear rates by dropping lump ore directly onto the apron feeder.
The client installed low level Gladiator Gen 3 Microwaveswitches in the chute between the apron feeder and the bottom of the stockpile. The Microwave switch turned off the apron feeder leaving 1 m (36 inches) of ore on the apron feeder when a low level was detected. This protected the apron feeder from high level wear problems.
HAWK's leading Microwave technology receiving circuitry avoids false trips even in dusty and sticky environments and can be programmed to track and report build up and maintenance requirements via Modbus, Ethernet or Relays.
Microwave non-intrusive switch:
- 1 x GSASUS (Remote controller)
- 1 x GMSB101XX (Microwave sender)
- 1 x GMRR101XX (Microwave Receiver)
- 2 x CA-GMR15M (Connection cable)
- 2 x MA4 (Window/weldment)
Low frequency stockpile level transmitter:
- 1 x AWR234SUXXXX (Remote transmitter)
- 1 x AWRT10T4XXXC15XX (10kHz transducer)
- 1 x FA10A-4 (10” ANSI acoustically isolated flange)
- 1 x C10-10-8 (High wear flexible focaliser cone for 10kHz)
Monitoring Settling Blanket in Sequential Batch Reactor (SBR)
The client had blanket carry-over problems, which affected his EPA license. The decant range was 0-1500 mm (0-60”).
Wastewater treatment plant
250 mega liter/day (65 million gallons/day)
We installed our floating Sonar transmitter, with auto scum cleaner, close to one of seven launders in the tank. During aeration the sonar transmitter, detected a high level blanket in suspension. Once the aeration period had stopped, the blanket settling was detected.
Once the blanket had settled 1 m (3.2 ft) below the liquid height, the launders were introduced and decanting started.
Using the ORCA floating sonar stopped carry-over into the launders. Automating the decant phase, based on the blanket settling, increased efficiency and saved time during the settling phase.
- Transmitter: OSIRDYX
- Sonar Transducer: AWRTS003S4XC6
- Sonar Cleanser/Float/Brackets: OSIRSCD
- Sonar Transducer SS Pole 5 m (16.5 ft): OSIRMEL5
Remote River Flooding Detection
A customer was looking for a reliable, cost effective level measurement device suitable for a remote, solar & battery powered remote telemetry installation. The system would be mounted out doors and needed suitable ingress and environment protection ratings for all types of climate.
The unit would be mounted on a bridge overlooking a river flood plain. The unit needed to be able to respond quickly if flood waters rose and threatened access to the bridge.
HAWK supplied the Miniwave Ultrasonic series for the application. The unit can be powered by as little as 7 volts with a suitable maximum range of 12 meters. The Miniwave is rated to IP67 which means it can be temporarily fully submerged in water without leaking.
The Miniwave can also automatically detect and set the low level measurement span which is useful for installations without schematic drawings to refer to for accurate parametrization.
Woodchip Bin Level and Truck Automation
The customer at a very large sawmill wanted to automate the truck pickup of their wood chips. Their current $500 device did not provide reliable consistent measurements. The customer needed aggressive pricing, but also wanted a reliable, continuous measurement of their wood chip bins. A high-level alarm was needed to dispatch a truck for chip pickup.
Being in northern Canada, with -40C weather, the device needed to work in snow, freezing rain, and ignore the constantly falling wood chips. HART communication was requested for networking and remote monitoring/programming. The device needed CSA GP approval, had to be a loop powered 24 VDC integral system and had to provide a volume calculation. The customer asked for a trial unit, and stated that if it works, they will standardize the device in 15 other locations.
HAWK installed a Sultan Acoustic Wave 10KHz integral system on a 90-day trial. Using the VOLUME TABLE in the software, a volume calculation was programmed using the Goshawk software. With remote technical assistance via Goshawk, the Sultan easily provided reliable chip bin measurements, gave correct volume calculations, and sent out a high-level alarm when the tank was full. The customer was so satisfied with the results that he placed an order for 82 more devices.
- AWI234SB10T4XXHXX: Sultan Acoustic Wave / 2-wire Integral / 24 VDC / 10KHz / HART
- FA8A-4: 8” flange
- FA8C-4: 8” angle flanges as an option
- C08-10-4 :8” cone
- HAWKLINK-USB: For Goshawk communication / programming / troubleshooting
Reliable Automation Control in 96 Food Silos
1. The customer had previous problems, where the level transmitters were unstable during filling operations.
2. The customer had used electro-mechanical level systems, where cables had broken off and gone through the feeder, causing major maintenance cost.
3. The customer wanted to provide a low cost communications package for the control room PLC’s.
4. The instruments must conform to dust ignition certification.
- The silos were sizes (A) 90 ft (27.5 m) Filling pneumatic (B) 50 ft (15 m) Filling Pneumatic. The products being measured were corn flour, wheat flour, rice flour, pre-mixes, grains, wheat, rice, oil seeds, canola, rape seed, offal etc. We provided 5 kHz transducers for the taller silos with powders and 10 kHz transducers for the shorter silos.
- The transducers were all non-intrusive and maintenance accessible, from the top of the silo. The transducers were self cleaning.
- We provided the customer with low cost ModBus communications, to reduce his installation costs. This also provided the client, additional diagnostic information in the control room, such as temperature levels in each silo, as well as levels etc.
We provided all the transducers with full Ex dust ignition certification, to comply with the local code.
- The transmitters were mounted in a remote location 2950 ft (900 m) away from the transducers.
- AWRT05S4XA20C6XX + FA10A-4 + C10-05-4 (5kHz transducer)
- AWRT10S4XA20C6XX + FA10A-4 + C10-10-4 (10kHz transducer)
- AWR234SUXXX (Remote transmitter)
CCD Thickeners in Gold and Gold/Copper Mining Processes
The customer at a large Gold/Copper mining company wanted to improve the automation control of its CCD circuit of five thickeners.
The problem was inconsistency of the floc dosing chemical to the CCD circuit which was causing settling problem in each thickener. This problem increased as different ore bodies of the mine were processed because of their different settling characteristics.
We first specified correct transducers to each thickener based on the compacted bed level density. We then provided each sonar transmitter with two analog outputs so we could monitor:
- Compacted bed level (high density interfaces)
- Hindered/Mud layer (lower density interface)
Our sonar transmitter tracked the two density interfaces. If the trends from the two interfaces tracked parallel the floc chemical dosing rate was correct.
If the trends parted with the lighter hindered/mud layer moving upwards in the thickener and the heavier compacted bed level moving downward in the thickener we increased the floc chemical dosing rate until the output trends again ran parallel.
Overdosing floc chemical also can reduce the compacted bed density so a feedback control loop is required for automatic dosing control.
- High power transducer: OSIRT302SHXC6
- Transmitter with two analogue outputs: OSIRDYX
- Auto scum cleaner with mounting bracket: OSIRSCA
- 3m mounting extension pipe: OSIRMEL3
Cement Powder Level Measurement
An Acoustic Wave level sensor is used to monitor the level of cement powder in a storage bin or silo. Each silo contains cement of particular type specifications. One or several silos will contain a particular type of cement product.
Most manufacturers or shippers of cement powder will have multiple storage silo level applications. Bins are generally fed pneumatically, or via air slide from a process or delivery vehicle. Product is normally removed from the silos via pneumatic transfer pipe or ‘clam shell’ or slide gate a downstream product manufacturing process, or road or rail truck.
Control system function:
The measured distance output of the sensor (communication, relay, or analogue) passes to a control system.
As level changes occur in the silo, the control system will continuously monitor the sensor output. Often the level output will be used for simple inventory management purposes. Cement silos may be holding vessels for material prior to bulk shipment by truck, train, ship, or bagging and packing for lower volume sale (at plants manufacturing the cement themselves). Silos may alternatively be storage vessels feeding a process which manufactures some concrete or mortar or mix product from the cement.
The control system simply needs to know how much of a given product is available, and where it is located at any given time in order to control outlet pipes or gates on silos to supply the correct material to a loading or packing facility, or the next part of a downstream manufacturing process. High or low alarm set points are often used in addition to the analog level measurement. In some cases, independent, redundant (separate) point level switch products are used for high or low level alarms, though this function can also be achieved by the Acoustic Wave instrument (using relay outputs) if required.
Advantages over alternatives:
Contact technologies such as guided radar (TDR) or mechanical dipping systems can work, but due to their contact with the material, may wear and eventually break cables or tapes.
Mechanical dippers will require maintenance and wear quickly in fine, abrasive cement installations. Guided radar and continuous capacitance based systems generate huge pull down forces on the silo roof, and upper cable mounting, so consequences of cable breakage or silo damage must be considered. Laser systems will not operate reliably over time in the presence of dust and will suffer from dirty buildup on lenses within a short time.
Traditional ultrasonics or non-contact radar may not have enough power to reliably penetrate through dust and may have difficulty in dealing with varied surface shapes of the material during filling and emptying phases, or suffer from false reflections from structures inside the bin. An Acoustic Wave level sensor mounted in the top of the silo will provide reliable, maintenance free measurement in dusty conditions of varied material filling and emptying profiles.
Instrument type selection and setup specifics:
Choose a 5 or 10kHz remote sensor with 10” isolated flange and cone for maximum reliability in detecting cement powder over typical distances of 10-160 ft from the mounting, with varied surface profiles. Integral types are inconvenient to set up once installed in inaccessible or high locations. If good access is available, then Integral types may also be used. Mount the sensor away from in-feeding cement flow and dust extraction systems. Position the mounting to have the clearest possible view down in to the bin (provide maximum possible separation from structures or ledges). Ensure that the cone end is clearly inside the main volume of the silo- not raised inside a mounting nozzle.
Generally, positioning the sensor vertically over the conical out feed section of the silo, or vertically within the central 2/3 of the silo roof, and clear of high level switches, structures, or in feeding material will give best results. Set ‘Fill Rate’ and ‘Empty Rate’ and ‘Fill Damp’ and ‘Empty Damp’ appropriate for the process conditions. ‘Gain’ or ‘Slope Distance’ may need adjustment to increase sensitivity in more difficult installations where returned echoes are too small. Be sure to set reasonable High (nearest) and Low (farthest) output levels even if relay control will be used. Set relays as required.
Magnetite Iron Ore Mine
A competitors Microwave blocked chute sensor was mounting high on a transfer chute and failing to perform reliably.
The physical switch suffers from the following:
- False trips due to rock trajectory
- Inability of early detection
- False trips from small amounts of build up
- Inability to sense blockages unless under physical contact (dependent on rock fall).
Proposal / Scope of Work
The image above shows the installed location, which required a 150mm circle, cut-out of either side of the feed chute to allow the installation of the sensor. The two new sensors are to be installed in CR003 & CR004 transfer chutes as the primary blocked chute sensor.
Year to date there have been 11 Secondary Crusher blockages.
The blockages require an average of 11 hours to clear (dependent on rock falls) which causes an average loss of 10kt per blockage.
The HAWK has more than halved the man hours required to clear blockages, by preventing the overflow of material on the secondary crusher feeder.
- Increase of 6.4 hours production following a chute blockage
- Blockage removal – Standard (11h), Trial (3h)
- 8h x 80% Util. = 6.4h
- Increase of 1500tph following a chute blockage
- 8h x 1500tph x 80% Util. = 9,600t saved per blockage event.
Crusher Blockage Detection
Crushers of all types such as Primary, Secondary, Tertiary or Auxiliary require precise control of feed height to work in optimal condition. Blockages of crushers are one of the major causes of throughput stoppage in comminution processes and these blockages are often caused due to choking the crusher throat whether the crusher is a jaw, gyration or roller type. With precise and accurate level control crusher feed height is able to be maintained at the optimum level ensuring maximum throughput without the risk of choking.
For many radar manufacturers crushers are an application that is simply passed over or installed units have failed due to the harsh conditions. The amount of dust generated by a crusher can be tremendous in of itself and with the addition of dust suppressing water sprays can completely attenuate radar signals.
HAWK’s Sultan Acoustic Wave Level Sensors operate on a completely different physical principle and uses a compression wave in the form of a sound pulse which easily moves around and trough particles of dust or water suspended in the air of the crusher mouth. The low frequency of these acoustic wave devices in comparison to other ultrasonic units in the market means pulse power is prioritised in design.
Customer’s application involved a secondary crusher taking feed from a belt directly from the plants primary crusher. Choking of this crusher would mean backing up the primary crusher and potentially choking it, resulting in the shutdown of the entire stream causing significant downtime while these blockages are removed.
Historically, the customer had relied on a competitor’s radar level instrument; however, in a few short weeks the radar had stopped working.
As can be seen in the photos, build-up, dust and water sprays are all present rendering radar technology totally unsuitable. Downtime due to blockage and damage to the crusher has resulted in significant losses in production and increases in maintenance costs.
Since installation and commissioning in April of 2016, the customer has reported no false/nuisance trips or instrument failure since installation that caused any downtime.
- AWR234SUXXXXX – Sultan remote transmitter
- AWRT20T4XXXC15XX – Sultan remote transducer
Level Measurement for Bitumen Trucks
Bitumen properties require that it remains at high temperature 180°C whilst being transported to prevent the product hardening. This heat is provided by a heating element located in the bottom of the vehicles tank.
Additionally, the product itself is extremely sticky and forms a thick coating on any structure within the vessel instantly making typical contact and mechanical measurement systems much more likely to fail.
Existing Installation: Previously the truck used simple level switches to detect bitumen level.
Due to the properties of the bitumen, the heating element at the bottom needs to be covered with bitumen all the time. If this element is exposed to air, Kerosene (present in the bitumen mix) will ignite which has happened 3 times in 2017.
The causes of these incidents were:
- Existing level switch became stuck due to product solidifying on it.
- The truck was on a hill meaning part of the element was exposed whilst the switch read a “good” condition.
- Existing level switch failed.
Alternative technologies were also tried such as pressure transmitters but temperature and pressure fluctuations caused issues with readings.
From previous experience with bitumen storage tanks HAWK was able to recommend the use of 2 Centurion Guided Radars (CGRs) located at the front and back of the tank to monitor the level at both ends of the heating element.
The units work as a safety device but it is expected that over time, it will be there primary level measurement so people do not have to climb on top to do manual dips. The accuracy of the HAWK units is so good that on flat ground the readings are within 10-15 litres of one another.
Qty: 2 x CGR: CGR2H13K08STB15V21XX180
Sand Filter Bed Tank Process
The customer had used conductivity probes to control high and low level water in their sand filter tanks. The probes were a problem because the coated up with slime and required routine cleaning.
HAWK installed Sultan Acoustic Wave, 2 wire loop powered 20kHz transmitter. The lower frequency 20kHz transducer provided excellent reliable control, during all sequences of the sand filter process.
Maximum range of the 2 wire 20kHz transmitter is 20 m (65 ft). When the sand filter was drained the instrument had no trouble monitoring the sand and the backwash sequence, which the client could not achieve with the conductivity probes.
Using the 20 kHz frequency transmitter, provided a solution to cover all environment changes, including rain, fog, snow, condensation, some frothing during back wash etc.
Note: Remote mounted transmitters, for the 2 wire loop powered range can be mounted up to 700 m (2300 ft) from the transducer, using belden 3084A cable.
- AWI2SB20T4XXXX + FA4A-4 + C04-4
- AWR2SBXXXX + AWRT20T4XXXC6 + FA4A-4 + CO4-4
Level Measurement for Coal Fired Power Stations
The client required reliable monitoring of the following level applications for an automation upgrade.
- Raw Coal Bunker
- Boiler Coal Bunker
- Coal on Belt Detector
- Shuttle/Discharge Wagon Positioning Control
- Raw Coal Bunker:
The raw coal bunker was 25 meters (82 ft) high. The level transmitter has to control the shuttle conveyor.
- Boiler Coal Bunker:
The boiler bunker was 20 meters (65 ft) high. The level transmitter was to control the shuttle conveyer. For application 1 and 2 we provided low frequency 10 kHz transmitters to overcome dust, rat holing etc.
- Coal on Belt Detector:
Monitoring coal on the conveyor belt. Range 1-5 meters (5 ft). For application 3 we provided 20 kHz integral transmitter to provide reliable profile height on conveyors.
- Shuttle Positioning Transmitter:
The maximum range was 50 meters (164 ft) for the shuttle conveyor and 195 meters (640 ft) for the coal discharge wagons. For application 4 we provided our 10 kHz positioning transmitter and for the discharge wagons we provided our 5 kHz positioning transmitter.
- Application 1 + 2: Coal Bunker Level Transmitter
AWR234SUXXXX + AWRT10T4XXXC15XX + FA10A-4 + C10-10-4
- Application 3: Coal on Belt Transmitter
AWI234SU20T4XXXXX + FA4A-4 + C04-4
- Application 4: Shuttle Conveyor Positioning (165 ft range)
(Master) AWR234SUXXXX + AWRT10T4XXXC15XX + FA10A-4 + C10-10-4
(Slave) AWR234SUXXXPS + AWRT10T4XXXC15XX + FA10A-4 + C10-10-4
- Discharge Wagon Positioning (640 ft range)
(Master) AWR234SUXXXX + AWRT10T4XXXC15XX + FA10A-4 + C10-05-4
(Slave) AWR234SUXXXPS + AWRT05T4XXXC15XX + FA10A-4 + C10-10-4
Train Unload Dump Stations
- To measure the coal in the dump station, as the rail wagon unloads, providing a stable and reliable output signal under all environmental conditions, with no cleaning requirement.
- To provide a backup non intrusive, low level and high level switch, in the train dump station.
- HAWK has provided many Acoustic Wave level transmitters, for applications to control automatically, train unload stations. Low frequency Sultan transducers are used to monitor under all environmental conditions, wet coal, dry coal, dust, noise, fast filling etc. The 10 kHz transducer selected has a maximum range of greater than 50 m (165 ft) and will cover adequately all changes in the bin automatically. The level measurement will remain stable during overfill conditions. The output will remain high until the level returns to the normal range. Because the power pulse of the 10 kHz is high, it is self cleaning. The focalizer cone is made from flexible polyurethane and is designed for this service.
- HAWK has also provided Microwave, low level and high level, non intrusive fail safe switches, that look into the bin through ceramic or polymer windows. The low level Microwave switch, provides an absolute guarantee to shut the feeders off on low level to protect them. The high level switches, would provide a guaranteed high signal, to slow the train crawl speed during unloading.
Part numbers for continuous level:
- Amplifier: AWR234SUXXXX
- Transducer: AWRT10T4XXXC6XX
- Flange: FA10A-4
- Cone: C10-10-4
Part numbers for low and high level switches:
- Amplifier: GSASUS
- Sender: GMSB101XX
- Receiver: GMRR101XX
- Connection cable-Qty 2: CA-GMR30M
- Window / Weldment-Qty 2: MA4
Lamella Thickener Control
The customer had problems with both of their lamella thickeners that they used to separate suspended solids from water. Lamella thickeners are high rate thickeners that use a series of angled impact plates to increase settling rates.
The problems for the clients thickener were:
- When the bed level came up to high and entered the plate region the efficiency of the thickener dropped.
- The bed would sometimes break up and flow over into the launders.
- We provided a sonar transducer that would operate under all operating conditions. The sonar monitored the interface bed column and controlled the under flow pump to prevent the bed entering the impact plate region. The sonar was installed with automatic cleaning.
- The sonar transducer can also provide a clarity output like a turbity meter. This alarmed when the bed broke up into pinfloc.