Dust Explosion
greetings,
well it sounds like the ugly head of static electricity has surfaced again.
Since your silo was closed the static electricity just built up since it could not disipate. If I were to handle such material I would hang steel or copper ground rods from the roof to near the floor of the silo to allow the electricity to go to ground, and clamp number four gauge copper wire to the rods and run it out side the silo to the ground mateing said wire with ground rods hammered into the ground at least 10 feet-3 metres plus.
I can speak from experience as I have been bitten by static build up from mining machinery used in underground mining that did not have a chain dragging on the floor to dissapate the static electricity-believe me the chains do work.
also realise that explosive energy is like water or electricity as it will take the easiest path hence your silo was blown up as the energy was directed upward.
this mechanics opinion.
lzaharis ■
Bis-A Dust Explosion
The only way to safely handle Bis-A is in an inert atmosphere.
Conveying systems handling Bis-A want to be designed as closed-loop systems with nitrogen as the conveying gas. The atmosphere in the bin is nitrogen also because the product is conveyed directly into the bin. The conveying gas exits the bin through a bin vent filter.
Analyzers in the bin and the conveying system monitor oxygen levels and are linked with control valves that add nitrogen to insure that the oxygen does not exceed 10%.
Dennis Hauch ■
Convertion From Pneumatic To Inerting
Thank you very much for your valuable comments.
Is it possible to convert a pneumatic conveying system to inerting system with minimum changes in the present system under NFPA 69 giudelines?
Can anyone help me on this.
Regards, ■
Nfpa Design
The requirements of both closed-loop system design and of explosion prevention must be addressed together when handling combustible dusts such as Bis-A.
The design requirements of closed-loop systems are a bit more stringent than open-loop systems but the fundamentals are the same.
And NFPA 69 is the proper reference for explosion prevention.
Dennis Hauch ■
Dust Explosion In Pneumatic Conveying
I feel, having explosion vents on the silo roof top would have averted the accident.
While making specification for dust collection system for dust partcles with static electricity, we keep the similar vents in Bag House. Was it there in the Silos?
Regards ■
Convert To Inert Gas
You can convert to inert gas , you either have a closed loop , or you vent your inert gas, then you need a inert gas generator and a cooler , or you handle your solid with hot gas .
It is common to find Pet Coque handling with inert gas.
Check with Paul solt, he might be able help you out.
Marco ■
Re: Explosion In Pneumatic Conveying
Design of closed-loop pneumatic conveying systems using an inert gas is common knowledge, you don't need a consultant to design these systems. Refer to many articles published in the literature for this design.
The main use of closed loop systems is to preserve the expensive inert gas by recycling it to the gas mover. Some air or oxygen does enter the system with the product or via other sources. Oxygen concentration must be kept below a specific level by blowing off some of the inert gas and injecting additional pure gas. Injection of this additional gas can be minimized by preventing air from entering the system.
A. T. Agarwal
Consulting Engineer
Pneumatic Conveying Advisors
polypcc@aol.com ■
Re: Explosion In Pneumatic Conveying
Sorry to say but you might be better off if you get somebody to help you.
Consultants can be helpful as they know manyof the tricks of the trade.
Paul solt is a very nice person , I believe he might even give you some hints for free.
Just give him a call, you will not regret it.
I did and we develop-ed a very cloise friendship.
I designed the hot pneumatic conveying system for Sponge iron, designed for pyroforic materials up to 750 degrees C.
It has been working for 8 years now 24 hrs a day 350 days a year.
Regards
marco ■
A Metalic Dust Fire After A Dust Explosion.
Design Of Pneumatic Conveying Systems
Design of dilute phase pneumatic conveying systems is described in detail in about 12 articles written by me and published in various Engineering Magazines. These articles cover both the process design and equipment design and also trouble shooting/problem solving of existing conveying systems. I will be glad to send copies of these articles for your use.
Regards,
Amrit Agarwal
Consulting Engineer
Pneumatic Conveying Consulting
email
olypcc@aol.com
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ■
Explosion In Pneumatic Conveying
Gentlemen,
Thanks for the replies.
Regards,
Ghouse ■