Page 1 of 2 12 LastLast
Results 1 to 10 of 15

Thread: Level Detection in Silos

  1. #1
    A CILLIERS Guest

    Question Level Detection In Silos

    Can somebody help me with a solution!!

    We have a cylindrical silo (16m high) with a conical bottom.
    Materials like Chrome is fed into the silo with a conveyor belt
    and a vibration feeder is used to discharge material.
    At this moment we are using a ultrasonic probe from the top
    of the silo to measure the level of material.

    The problem is that when the material level goes into the cone part of the silo, the level readings starts jumping around.
    Another problem is the accurracy of the level due to the profile
    of the material when it is fed into or pulled out of the silo.
    There is also a lot of dust when material falls into the silo that is influencing the ultrasonic.

    Is there any better way of measuring the level that will overcome my problems? Any suggestions welcome!!!

  2. #2
    Mike Cannon - Belsco Services, USA Guest
    Welcome to the world of level detection salesman.

    You should have started out by weighing the silo, or as a minimum looked at the cost to retrofit with load cells. If it is a 3 point or 4 point silo, you can put a weighing device under one support and get 2-4%. You can do all support points and of course get better accuracy. If it has a full continious base ring, adding load cells is difficult unless it is free standing on 4 legs.

    Ultrasonics DO NOT like dust or cones or varing angle of reposes.

    Your only other option is to put RF or vibratory, or contact probes every 3-5 meters up the side and hope they work.

    Strain gages are available, but should only be used if the supplier knows what he is doing.

    Send me some digital pictures and I will try to help you more.

  3. #3
    Join Date
    Jun 02
    Posts
    7

    LEVEL DETECTION IN SILOS

    You can try with a microwave level. This kind of level is provided with a cable that is placed from the top to the bottom part of the silo. This level is furnised by Endress + Hauser (type LEVELFLEX) We have good experience in hoppers ( 4 m height) I don`t know if it is valid for silos of 16 m.

    Fernando Arderus
    STOLZ, S.A.
    http//www.stolzsa.com

  4. #4
    Mack Yarbrough Guest
    Ultrasonics, when properly installed and tuned will work in dusty atmospheres with varying angles of repose. The issue in the cone area is an inability to adust to the cone as the material level goes down. Transducer location and aiming are the most critical in this type of application. The transducer should be located 1/2 radius opposite the fill point and not between the fill and any dust collectors. Aiming of the transducer is slightly past the draw point. This will give the most consistent performance. Using variable gain will also be of benefit.

    The use of level to convert to weight is, at best a 10% system due to angle of repose, compaction, specific gravity. By the inverse, using weight to convert to level is also, at best a 10% system for the same reasons. If the intent is to understand how much room is in the silo, then ultrasonics or yo-yo will work. The use of radar and microwave, guided or not, is dependent on the materials dielectric constant. Anything less than a DC of 2 is suspect. Guided type are in contact with the material and exhibit a pull of approximately 7,000 to 10,000 psi on the connection point at the top of the silo. Radar will also have the same issues with angle of repose, etc.

    Direct support weight will give weight, but a high level probe would be recommended to prevent overfill.

    Depending on the support structure, bolt-on strain gages from KM may also provide a more accurate weight system that meets your requirement

  5. #5
    Roy Zielinski Guest
    I need a little more information on your application before I can recommend a specific replacement model. What are the temperatures and pressures inside this silo? What is the diameter of the Silo? Is the silo smooth wall like in concrete, welded steel, or bolted steel, or is it rough as in corrugated construction? What is the angle of the hoppered bottom? These attributes all affect the accuracy and reliability of Ultrasonic level measurement. Have you verified that the temperature compensation in your system is working correctly? How close is the ultrasonic transducer mounted to the filling point? Have you contacted the manufacturer's Tech Support and asked for assistance? Do they and the existing level system have the capability to look at the return echo signals via modem?

    What is the particle size of the "Chrome" and what are the other materials? What are their densities and angles of repose? Are the materials electrically conductive, and will they leave a coating on objects in the silo? Do you need a level measurement while filling? How often do you need a new measurement? What types of outputs are desired if any, or would a display only suffice? Where will the display be located? Is there a need to remotely query to level measurements offsite as for vendor-managed inventory?

    Are there any chemical compatibility issues with these materials? Do any of the materials present a dust ignition hazard? Are there any obstructions, mechanical supports, or flow aid devices in the silo?

    All of these characteristics and requirements will influence the selection and resultant dependability of the "Bindicators."

  6. #6
    mky Guest

    Thumbs up

    Dear Sir,

    The level indicators for bulk solid silos were manufactured by us had been used under similar or worst conditions since more than ten years, in Turkey and abroad. we can give you more information if you contact us.

    Best regards
    Mustafa Kemal Yunel

    Yunel Elektromekanik Co. Ltd.
    Esat Caddesi No= 34/5
    Kucukesat 06660
    Ankara/Turkey
    Phone = +903124193285
    Fax = +903124193289
    e-mail = mky@yunel-birlik.com.tr
    URL = www.yunel-birlik.com.tr

  7. #7
    mohamedasadulla Guest
    I saw your problem. may be can you solve this using nucleonic level guages. as these level guages are fitted outside the silos and moreover they are not disturbed by dusty atmosphere. but at present i cant tell you the exact manufacturers. if i come across i shall inform you.
    Mohamed Asadullah
    asadullahasad@rediffmail.com

  8. #8
    Frank Wengler Guest

    Lightbulb

    We are manufactures of level devices since many years. For difficult conditions such as high dust and vibrations, I recommend the yo-yo principle for measuring level. It seems to be a old fashion principle, but you would be surprised how much microprocessor intelligence it has. However, the sensing weight of the yo-yo goes straight down to the product and up again. There is no influence of dust, vibration or noise of pneumatic conveyors. And it is not depended on the dielectric of the material. If you need some more information, please contact me:


    MAIHAK AG
    Poppenbtteler Bogen 9b
    D-22399 Hamburg
    Telefon 0 40- 2 78 94- 312
    Telefax 0 40- 2 78 94- 362
    frank.wengler@maihak.de

    www.sick-maihak.de
    http://www.sick.de/de/products/categ...nitors/en.html


    Frank Wengler

  9. I can not claim to be expert of level indicators for silo. The level indicator manufacturers would be the right people for specific information. Present day, many varieties have come, however, please be careful that the particular type will be ideal for particular nature of application only. There is no level indicator, which is ideal in all situations. At one stage following types were very popular :
    1) Descending weight type. This is mechanical type of indicator, reliable in certain situations. However, material should not contaminate / stick on rope / tape. Also, if the lumps are of very big size, they may strike the weight when it is going inside the silo. This type of indicator has been reliably used in silos storing crushed coal of (-)40 mm.
    2) Paddle type indicator. This will need protection from falling lumps.
    3) Deflection / contact type indicator. This is more used at silo top where piling of material deflects the probe
    4) Nucleonic type is virtually out of use in India since about 15 years, because it needs authorized people from atomic energy institutes at regular intervals to certify that radiation level is within limit, etc.

    The other respondents have already provided interesting information on this subject. While choosing the indicator, its behaviour under falling material, variation in moisture content etc should be properly analysed.

    Once the level indicators are installed, it is essential that these should be regularly cleaned and serviced for reliable function because they are subjected to material contamination and adverse conditions, all the time.

    Regards,
    Ishwar G Mulani.
    Author of Book : Engineering Science and Application Design for Belt Conveyor.
    Email : parimul@pn2.vsnl.net.in
    Tel.: 0091 (0)20 5882916

  10. Level Detection in Silos

    Usually you want to sense level at the same time you are filling
    to avoid overfilling - means material falling down through a ultrasonic, radar/microwave or lazer beam - not great!
    Surprised Bindicator has not offered their "phase tracker" tape device that hangs down into the bin - used to be "Celtek".
    Endress & Hauser "levelflex" cable is similar but not as sophisticated.
    Funniest thing I ever saw was radar/microwave beam trying to
    see the level of plastic pellets that are invisible to radar.

    Nothing will measure down into a cone properly.
    If signal is 4 - 20 milliamps the cone volume which could be many tonnes could sill be there with 4 milliamps showing silo empty.

    I do like the various "yo-yo" devices but they do need some maintenance to keep them working - mechanically complex.

    If you can live with just point level - HiHi, Hi, Lo, LoLo instead of continuous measurement your choices are limitless - I like
    tuning fork devices - E&H vibratrol or similar.
    Rotating paddles can stop working - mechanical action.
    Some people like plastic insert on bin side & proximity switch outside - "efector" or similar.

Page 1 of 2 12 LastLast

Similar Threads

  1. On Line Belt Rip Detection
    By Jimmy Hadinata in forum General Aspects
    Replies: 3
    Last Post: 5th January 2005, 20:19
  2. powder silos level measurements with ultrasonics
    By Marcos M. Pimenta in forum General Aspects
    Replies: 5
    Last Post: 13th November 2000, 15:40
  3. inserts in powder silos
    By Marcos M. Pimenta in forum General Aspects
    Replies: 1
    Last Post: 13th November 2000, 9:40
  4. Powder silos containing multiple inserts
    By Ian Whitlam in forum General Aspects
    Replies: 2
    Last Post: 13th November 2000, 9:35
  5. A/2000 Silos, Hopper, Bins & Domes Vols. I-IV
    By Author in forum General Aspects
    Replies: 1
    Last Post: 10th November 2000, 17:12

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Single Sign On provided by vBSSO