Does anybody know of a non-nuclear continuous in-line density meter for an abrasive mining slurry in a 12" pipe?
Our customer wants to go 'green'. He wants to change from nuclear devices to avoid safety officer, nuclear source storage, transport and disposal costs, as well as surveys and wipe tests.
We tried ultrasonic density devices, but > 10% solids, the signal is so noisy it has to be heavily damped. The resultant signal is far from the true average.
We tried microwave techniques, but mining slurry conductivity is too high and its dielectric constant far from constant...prerequisite for such systems. Any comments would be welcome.
One mine I worked at we had DP cells on the cyclone feed lines.
Taps into the rubber lined pipe about 3 feet apart with water flush. It worked ok for the most part except every now and then one of the taps would plug up.
Nuclear density is the most reliable and trouble free method by far.
I don't see what's not green about it.
Thank you for your comments. The trouble I had with DP with flushed ports was change of slurry velocity in the pipe. Most of the time you don't know whether you're measuring density or mean velocity change.
By non-green nukes I meant all the costly problems that go with them,as well as unknown health hazards, storage and disposal.
Well, sure there are licensing issues, but there are NO unknown health issues, and disposal is solved if governments want to implement the solution. I concur with Roy. They are the best technical solution, and calling them non-green is simply wrong.
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nukes are plagued more by mis-management than the licenture issues, that said, you have to engineer a d/p meas, they do work, but you'll have to spend the green to get it done
there are a number of measurement methods, but with slurries you'll have to do your engineering work up front, otherwise you'll have a white elephant to add to your green credentials...
slurries are tough
You might try Cidra Sonatrac.
This uses ultrasound but is not an ultrasonic meter.
Austin: Regarding NON-Nuclear density metering systems.
The long held desire in the mining and dredging industries has been for a highly accurate density sensor and mass flow system to replace existing nuclear domain gauges has at last been fulfilled. This major advance comes in the form of a continuous in-line system suitable for dredging and mining slurries for pipe sizes 2" - 40" diameter. The system may be calibrated in % dry solids, wet density and wet or dry mass flow units. The density meter incorporates a linear, direct sensing of mass per unit volume, as a refreshing change from costly and hazardous nuclear techniques. The system is vibration and temperature insensitive, environmentally friendly, buriable on land and roll compensated for dredging at sea. The mass of the slurry is continuously measured using patented, high resolution density transducer as the slurry passes through an obstruction free flow tube. The flow tube is of optimum length to provide a truly representative continuous sample of the slurry, whose density signal is interrogated 110 times per second to ensure accurate and repeatable sensing. The flow tube also provides the necessary straight lengths of upstream pipe run for using an integrally mounted, high quality magnetic flow meter used when mass flow is required. The density meter flow tube has reinforced walls up to typically 1" thick, lined with a natural gum rubber liner. As such, extremely long life is assured, even with the most aggressive media containing sharp rocks, sand and tailings. The flow tube is site replaceable and a warning 'Replace Flowtube' relay may be provided. Both the low natural frequency of the density meter, and the anti-vibration algorithm in the electronics ensure vibration is well compensated. The electronics actually rejects the 'pink' media noise and averages the resultant dual mode signals at 110Hz to obtain a highly accurate measurement of mass per unit volume. The system is so sensitive that variations in gravity at different parts of the world are accounted for in a true mass system. The system is uniquely USA NIST and Canadian Weights and Measures traceable. At the press of a button on the remote electronics, the complete system may be on-site diagnosed and re-validated to it's internally traceable calibration, without the need for test weights. Displaying and recording, analog signals and digital communication of production results is standard.
Sciam Worldwide DM3 non-nuclear units are your best choice for removing all hazardous nuclear devices from your mining operations. These units can be fitted to be operated with a significantly reduced maintenance burden and greater benefit from increased accuracy over nuclear units. If there would be any questions you might still need answered after visiting the Sciam Worldwide website, access the Sciam Inquiry Form located at http://www.sciamworldwide.com/enquiry-form/ and type in B. Moore in the "Comments" section and I will make sure personally that you are contacted to answer any questions you may have and to provide any additional information needed.
Interesting - and frustrating.
Interesting in that if it does what is claimed, it seems a reasonable device.
Frustrating for the fact that it avoids anywhere stating how it works.
I hate it when the operating principle is deliberately not disclosed and you can sense the care with which this has been achieved.
But it inevitably results in some clumsy technical writing and I am always reminded of those snake oil sites where they "extract energy from the zero point field" or how some magnetic device "lines up the molecules" in fuel so they burn better.
I start to imagine, rightly or wrongly, that someone is trying to slip something over on me.
It measures mass per unit volume directly.
It can't be that terrible or so secret.
If you want to keep things secret you don't patent them.
This is claimed to be patented.
Reading the FAQ and the description of the "rubber flow tube supported by the density transducer" all of which moves by just a few microns, I would normally deduce that this is one of two common methods:
1) Vibrating element e.g. as discussed above
2) Force Balance e.g. Hallikainen Gravtrol
Or maybe some variant of either or a hybrid of the two?
But resonant frequency devices don't measure density - mass per unit volume - directly.
Vibrating element sensors measure mass, the resonant frequency is a function of the mass of the system. Not density.
It just so happens that the mass changes with the density of the fluid - and a few other things that have to be calibrated out - and the device is calibrated so as to extract the density.
The Gravitrol doesn't measure density directly either. It measures weight. The weight happens to vary with the density of the fluid flowing through it.
In the Gravitrol the flow tube is horizontal and tends to sag due to its weight and the fluid inside. As it sags a balancing force is applied to maintain it in its original position. The balancing force is a function of its weight and hence it can be calibrated against the fluid density.
So how does this work?
A new method I'd be very interested in. And the patent claim could then refer to the method which can be disclosed to us.
Or it is one of the above methods and the patent relates to some protective aspect of the implementation.
In the end, if it delivers the stated performance, then where is the problem telling us how?
Engineers like to know things like this. Keeping it from them in a clumsy way makes them suspicious.
With pretty well any technology, and especially when the data sheet will have to convince engineers, there is usually an in depth discussion of the measurement principle if it is new, or a simple statement of which principle is used if is widely understood.
So, my two guesses were vibrating element or Gravitrol force balance method.
It's a close call but the limitations on orientation imposed, I'd opt for the force balance principle of the Gravitrol - or a variation of that.
But why not tell us how it works rather than how it does not?
You can always go with a Coriolis meter. you will be able to get you flow rate, temp, density, 2phasing and a few other helpful measurements.
Perhaps a tunning fork system with density computer could be an option. eg: Endress & Hauser Liquiphant M FTL51 and FML 621 density computer.
If one were to use a tuning fork I would rather go with the 7828 long stem from Emerson. This is both rugged and robust.
Abrasion may mean a periodic lab check and k0 offset correction.
They have been used on a variety of slurries including chalk slurries from quarries in the cement industry and are used in towable arrays to test river muds.
The construction is impressively resistant to damage. There only thin spot is the small half moon thin wall over each of the piezos at the root of each tine.
In general the Liquiphant and Squing tuning forks do deliver reasonable density but the construction is far less rugged - they are designed as economic level switches and I would not like to commit to their long term survival in an abrasive slurry.
The accuracy is probably not as good as the 7828, itself only 1kg/m3 but with all the necessary algorithms including percent mass.
But this is a 12" pipe where we won't get a uniform homogeneous flow.
The best a tuning fork can do is make a point measurement.
It will sample the density wherever you can locate the tines in the flow. The long stem version allows you to locate the tines away from the pipe wall. Ideally in the centre third of the pipe line. This is usually the most representative part of the cross section, subject to the pipe layout delivering a reasonably laminar flow at that point.
But this is why I find the full bore device described above interesting.
It is deriving the density not from a point measurement but from a full pipe section over the length of the sensor. It may deliver a less accurate measurement but it may compensate by being more representative.
If only I knew how it worked!
I am writing to address a few of your concerns/observations as 1) they are indeed valid and 2) there have been a few responses via Sciam [salesmen] that haven't directly addressed your points raised.
When debuting the DM3 technology, we were very cautious to unveil all of the inner workings as it is such a simple method and we were a relatively unknown company. During each initial conversation with suppliers, re-sellers, and competitors a buy out conversation was offered without fail. Even with a [worldwide] patent, we were concerned about imitations before we were able to make a name for ourselves and the DM3 technology.
Appearing "to slip something over" certainly wasn't our intention, and we apologize for any confusion and/or frustration this caused.
In the few months that have passed, we have made major strides towards recognition as a standard method of density measurement within the mining, dredging and wastewater industries. Most recently, we were identified as the standard unit of measurement for the City of Jackson wastewater treatment plant by CDM Smith.
To briefly describe how the DM3 works, the entire contents of the abrasion resistant rubber flow tube is constantly weighed using a custom load cell. Mass is derived by compensating for the exact gravitational force at the particular install site. With a known volume of media and the measured mass, density is calculated.
The term direct refers to the basic calculation of density being made on two measured values without the inference of any information.
We are more than happy to go into further detail on the technology and it's use in specific applications. Alternately, our inventor and Director of Engineering often speaks at industry conferences and exhibitions - he will be at PIANC next week.
the status of your most current interest in the newest advances in Density Flow Measurement. (http://www.sciamworldwide.com/). Please log onto our website, if you have not done so lately. We have made a few updates.
I'm here to support you and answer any questions you have regarding our DM3 Non-Nuclear Density Meters.
- better accuracy
- lower lifetime costs
- handles vibrations and tilt
- 2" - 40" diameter pipes
- wide variations in temperatures
We have developed a non nuclear density gauge that is faster than a nuclear gauge and accurate. The gauge is suitable for magnetite type slurries in coal washplants.
We are a Queensland based company that has sold this gauge and others of our measurement instrumentation for materials processing internationally.
My email address is firstname.lastname@example.org please email me for more information and to let me know whether you have already found a solution.
I am interested in your device. Please contact me off list.
Walt Boyes, FInstMC, Chartered Measurement and Control Technologist
Life Fellow, International Society of Automation
Editor in Chief, Control and ControlGlobal.com
Has anybody tried the DM3 by Sciam Engineering? Any reviews has changed.
We have a Salt slurry where we want to measure density. Any recommendation for best available method to measure density.