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Thread: Rail Car Unloading

  1. #1
    Bala Guest

    Rail Car Unloading

    Does anyone share of their experience on unloading virgin plastic pellets from rail car using 8"OD line size (vacuum side). Normally the rail cars are unloaded using 4 to 6" conveying line size.

    Any help would be highly appreciated.

  2. #2
    Dennis Hauch - Freeport, TX, USA Guest

    Railcar Unloading

    Bala,

    Ive had quite some experience in this area and will be happy to share it with you.

    There are perhaps two basic reasons that merit stepping of the conveying line from 6 to 8 1) increasing or maximizing the conveying rate and 2) accommodating a receiver location more than, say, 50 meters from the railcar unloading spot.

    If the existing unloading line is 6 it is very likely that it can not be replaced with an 8 line without, I say without, replacing the vacuum blower and the blower motor. Can be expensive.

    If, however, the existing unloading system is 8 a 6x8 concentric reducer may be located just downstream of the railcar connection. Be aware that the velocity in the 6 section under the railcar is near double what it normally would be for a straight 6 system. This would be a concern if the plastic pellets that are being unloaded exhibit any tendency to form streamers.

    I trust this helps, dont hesitate should you have any questions.

    Regards,

    Dennis Hauch

  3. #3
    Bala Guest

    Re: Railcar Unloading

    Originally posted by Dennis Hauch
    Bala,

    Ive had quite some experience in this area and will be happy to share it with you.

    There are perhaps two basic reasons that merit stepping of the conveying line from 6 to 8 1) increasing or maximizing the conveying rate and 2) accommodating a receiver location more than, say, 50 meters from the railcar unloading spot.

    If the existing unloading line is 6 it is very likely that it can not be replaced with an 8 line without, I say without, replacing the vacuum blower and the blower motor. Can be expensive.

    If, however, the existing unloading system is 8 a 6x8 concentric reducer may be located just downstream of the railcar connection. Be aware that the velocity in the 6 section under the railcar is near double what it normally would be for a straight 6 system. This would be a concern if the plastic pellets that are being unloaded exhibit any tendency to form streamers.

    I trust this helps, dont hesitate should you have any questions.

    Regards,

    Dennis Hauch

  4. #4
    Bala Guest
    Dennis,

    Thanks a lot for the reply. I would like to inform you that the system is being newly installed. The rail car receiver is 560 ft away from the the rail car. There is no way that we can bring the receiver near to the rail car. Since, the rail car material oultet is only 6" we need to make the 6" to 8" rail car adapter. The conveying line is 8"

    Do you have any experience on using 8" line in the vacuum part of the rail car unloading?

    By the way if I need to talk you, how can I reach you? any contact no.

    Thanks again
    Bala

  5. #5
    Dennis Hauch - Freeport, TX, USA Guest

    RC Unloading

    Bala,

    Be aware that the distance to the receiver, 560 ft, is quite long for a railcar unloading system and will greatly compromise the conveying rate from the railcar, even though the conveying line is 8.

    The reason is straightforward. In a vacuum arrangement, the vacuum capability of a PD blower is, nominally, 15 Hg, which equivalent to 7-1/2 psi. At a system pressure of 7-1/2 psi we would estimate, in the absence of calculations, that the expected conveying rate would range from 20,000 to 30,000 lb/hr. The nature of plastic pellets that you are conveying will also affect the expected conveying rate.

    Call or e-mail should you have questions. The numbers are (979) 297-0361 and hauchds@computron.net, respectively.

    Regards,

    Dennis Hauch

  6. #6
    Line dia depends upon the required conveying rate. Since the blower pressure drop of vacuum systems is about 1/2 of that for pressure type systems, the only variable is line diameter. You can use a stepped pipe line to reduce the pressure drop. These steps can be 6/8/10/12 inch.

    We will be glad to design this conveying system for you having more than 100 years of experience in this field.

    Regards,

    Amrit Agarwal (Tim)
    Pneumatic Conveying Consultants
    polypcc@aol.com,or pccsolt@enter.net

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