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Thread: Pneumatic Container Unloading

  1. #1
    abreezgillani Guest

    Pneumatic Container Unloading

    Greetings all!
    I am new to this forum as well as the industry. I have taken up a project related to silo container unloading of soda ash. In the present process, we use Jumbo bags (1.25 Ton) which are lifted using an EOT crane and fed into a hopper which transfers it to a Macwaber Densevyor system and a 2.2 bar compressed air pumps it up to silo that are 32 m high. However, the process is quite labor intensive and a lot of risks are involved. Moreover, since our consumption is above 350 tons per day across 6 silos, it would be better if we could go for container unloading.
    I came across Ehcolo CTT unloader, which is attached directly to the container that can be tilted on a truck. The only worry I have as of now is the feasibility of the process. They use a blower system attached to the rotary valve to push the material to the silo, but since in my case the silo height is >30 m, the pressure drop can be significant. Can I please get some guidance related to the pressure drop calculations and the air flow rate required for my particular process. I have attached the specifications of the silos. Silo Specifications for Soda Ash.pdf
    I would highly appreciate that.


  2. Why don't you get Soda Ash in bulk tankers ? No need to have separate conveying system.
    Convey directly from tanker into silo. Might need a land based blower /compressor if there
    is no on-board blower.

    Macwaber Desnoveyor now that is something from 80's.


  3. #3
    abreezgillani Guest
    Dear Mantoo,

    We are importing Soda Ash from Bulgaria, which comes in 1.25 ton bags in a 25 ton container as of now. We are planing to change that to a 24 ton liner bag. Since bulker loading process requires us to have a separate facility where soda ash is loaded in bulkers, we thought it would be convenient if there was some mechanism which transfers the material directly from the shipped containers.
    We got in touch with Macwaber and Ehcolo, both are pitching in their ideas and seem convincing enough. But the constraint with Ehcolo is that they are suggesting a blower to pump soda ash to silo's that are 33 m tall, and I feel that might not be feasible for the longer run.
    Any suggestions will be highly appreciated.


  4. 33m vertical is achievable with lean phase system only problem is excessive
    degradation of soda ash. If degradation is not an issue then it is ok. If not
    then you will need to put your densoveyor in a pit with a little hopper which
    can be fed from the container. You will still need the container tilting frame.


  5. #5
    What is the crane capacity?
    I can supply a tilting device. There is no need for a pit & the associated drainage to protect the hygroscopic product.
    Bag-in-box product is usually carried in non-preferred 9m containers with a letterbox door adding to the complexity, specialisation & cost. Such tilting trailers have on board blowers.
    Even if you need a bigger EOT my system will be economical.
    Carting soda Ash by tubs (powder tankers) by road from Bulgaria is prohibitably expensive.
    I was in charge of engineering soda ash imports from Utah, via Portland & Philippines, to the Eramet nickel facility on Halmahera, Indonesia. That was containerised: but no letterboxes on site.
    John Gateley

  6. #6
    Soda Ash can develop lumps during transit. Ours were 90mm at times. I would provide air bleed for fluidisation to get the stuff out of the liner in the first place. Then you will need an attritor upstream of any pneumatics.
    Bulgaria is only 4 days away. Have you balanced the container logistics with the silo capacity to see if you could just leave it in boxes until needed?
    John Gateley

  7. #7

    For What Its Worth!

    Your present system was workable although there is a lack of information regarding how many containers can be emptied at once.
    Bag in box operations typically take 2 hours considering set up, blowing & disconnecting.
    One of your problems is the danger presented to, and by, forklift drivers. FIBC's stacked 2 high will have fallen against the container walls & also require an operative to climb, initially with a stepladder, and hold the loops of the top row open for fork entry & engagement. This procedure potentially violates safety no matter what & the stepladder height must be adjusted once the first 4 bags are out of the way: assuming the container is in the open air. Inside the container the darkness increases as more bags are removed. Vision is difficult & the loop lifter is always presented with heavy steel forks approaching the 2 loops he is holding against the container roof while he is standing on the lower bag next door. Whatever anybody can provide it is still a precarious operation. Of course you could use pallets & expect the problem to go away: except that you have to have a good Pallet Change Voucher (PCV) system in operation with the 280 pallets requiring storage. Most pallet collectors entertain about 520 pieces: less with a curtainsider. So unless you have an onward market the pallets will accumulate in your yard. As they do in most yards.
    If the bag in box business has gone too far, I suspect, then you have to account for the cost of the liner. This is considerable & returning is rarely an option. The carrier stuffs it under the trailer hose box & either disposes of it of uses it as weather protection around his yard. At least pallet recycling can be regulated properly.
    Your problem is simply that you are using 20' boxes instead of 40 footers. A 40' box will enable single layer loading. There will be very little difference in the tariff: the weight difference is negligible; 70% of the world container fleet is 40'. The operator can stand/kneel on the bag ahead of the forktruck & is therefore better isolated from fork impingement.
    Basically, no pallets, liners or fancy stupid tipping 30' trailers
    Last edited by johngateley; 1st January 2019 at 4:47. Reason: trailers was .railers
    John Gateley

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