controlling the explosion risks within hammer mills
DESCRIPTION
Grain and feed processed within hammer mills is common fuel for dust explosions due to the nature of its handling and storage. Any time that feed such as grain, meals and flours is handled or moved, the fine organic dusts are at risk of burning and exploding.TRANSCRIPT
Grain & Feed Milling Technology is published six times a year by Perendale Publishers Ltd of the United Kingdom.All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. ©Copyright 2013 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1466-3872
Digital Re-print - January | February 2013 Controlling the explosion risks
within hammer mills
www.gfmt.co.uk
Grain and feed processed within hammer mills is common fuel for dust explosions due to the nature
of its handling and storage. Any time that feed such as grain, meals and flours is handled or moved, the fine organic dusts are at risk of burning and exploding.
Explosion causesA fire or explosion results from ignition
of combustible material (dust, gas or vapour) when mixed with oxygen in the air. When this takes place inside a grain silo, process or storage enclosure, the rapid rise in pressure could cause a violent explosion in millisec-onds, placing personnel and property at risk.
Just a few burning embers entering a dust collector are enough to trigger a dust explosion. Likewise, combustible material conveyed into a storage silo could become the nucleus of a fire. Sparks or smouldering particles from hammer mill operations may spread from the mill to other more vulner-able equipment.
Most materials handling, processing and storage equipment is not designed to resist the pressure of an expanding flame ball which proceeds below the speed of sound in air – known as a deflagration – as com-
pared to a detonation, which exceeds the speed of sound in air. Most grain dusts are combustible and can cause an explosion, but some types are much more dangerous than others, especially dust associated with corn or sugar.
The effects of accidental fires or explo-sions can be devastating in terms of lives lost, injuries, damage to property and the environment, and to business continuity.
Serious secondary effectsGrain dust explosions can have a cascade
effect. Grain dust that has settled on floors
or walls can be thrown into the air by a dust explosion, thus providing fuel for secondary explosions. Often, these secondary explo-sions cause more damage than the first. In this way, a dust explosion can jump from room to room or from silo to silo. This is a common phenomenon in grain dust explosions. For example, one of the most dangerous areas for grain dust explosions is in the bucket elevator or conveying system linked to a silo. The grain is always in motion, so dust is constantly generated.
Protection measures An explosion risk assessment will typi-
cally recommend that a series of protection measures be implemented. These range from investment in protection equipment to improvements in housekeeping to elimi-nate the build-up of deposits of combusti-ble dust which may accumulate on beams in the factory. These may be disturbed by a primary explosion in the process equip-ment and result in a more severe secondary explosion.
Codes and standards are now very clear in requiring isolation of vented equipment to prevent secondary explosions, which typi-cally have much greater potential for damage and destruction.
Controlling the explosion risks within hammer mills
by Kevin Spiess, EMEA sales manager for explosion protection, BS&B Safety Systems,
United Kingdom
SparkEx Spark Detection and Extinguishing system
Grain&feed millinG technoloGy10 | January - february 2013
FEATURE
Grain and feed processed within hammer mills is common fuel for dust explosions due to the nature
of its handling and storage. Any time that feed such as grain, meals and flours is handled or moved, the fine organic dusts are at risk of burning and exploding.
Explosion causesA fire or explosion results from ignition
of combustible material (dust, gas or vapour) when mixed with oxygen in the air. When this takes place inside a grain silo, process or storage enclosure, the rapid rise in pressure could cause a violent explosion in millisec-onds, placing personnel and property at risk.
Just a few burning embers entering a dust collector are enough to trigger a dust explosion. Likewise, combustible material conveyed into a storage silo could become the nucleus of a fire. Sparks or smouldering particles from hammer mill operations may spread from the mill to other more vulner-able equipment.
Most materials handling, processing and storage equipment is not designed to resist the pressure of an expanding flame ball which proceeds below the speed of sound in air – known as a deflagration – as com-
pared to a detonation, which exceeds the speed of sound in air. Most grain dusts are combustible and can cause an explosion, but some types are much more dangerous than others, especially dust associated with corn or sugar.
The effects of accidental fires or explo-sions can be devastating in terms of lives lost, injuries, damage to property and the environment, and to business continuity.
Serious secondary effectsGrain dust explosions can have a cascade
effect. Grain dust that has settled on floors
or walls can be thrown into the air by a dust explosion, thus providing fuel for secondary explosions. Often, these secondary explo-sions cause more damage than the first. In this way, a dust explosion can jump from room to room or from silo to silo. This is a common phenomenon in grain dust explosions. For example, one of the most dangerous areas for grain dust explosions is in the bucket elevator or conveying system linked to a silo. The grain is always in motion, so dust is constantly generated.
Protection measures An explosion risk assessment will typi-
cally recommend that a series of protection measures be implemented. These range from investment in protection equipment to improvements in housekeeping to elimi-nate the build-up of deposits of combusti-ble dust which may accumulate on beams in the factory. These may be disturbed by a primary explosion in the process equip-ment and result in a more severe secondary explosion.
Codes and standards are now very clear in requiring isolation of vented equipment to prevent secondary explosions, which typi-cally have much greater potential for damage and destruction.
Controlling the explosion risks within hammer mills
by Kevin Spiess, EMEA sales manager for explosion protection, BS&B Safety Systems,
United Kingdom
SparkEx Spark Detection and Extinguishing system
Grain&feed millinG technoloGy10 | January - february 2013
FEATURE
Innovations for a better world.
Success comes with the original product. Quality always pays off. Bühler is setting
standards in the grain processing industry for more than 150 years. Whether you
grind wheat, corn, rye, oat, buckwheat, soy, or malt grain – our processes and
equipment are finely tuned to get the most from your grain. And this kind of pro-
cess quality quickly pays off. The highest flour yields and best product quality
ensure fast return on investment. www.buhlergroup.com
Bühler AG, Grain Milling, 9240 Uzwil, Switzerland, T +41 71 955 11 11, F +41 71 955 66 11
[email protected], www.buhlergroup.com
Visit us at the IDMA 2013
in Istanbul (April 4 – 7, 2013),
Hall 10, booth no. B2
Bespoke systems My organisation, BS&B Safety Systems,
has launched a bespoke combustible dust fire and explosion prevention system for hammer mills based on established systems developed for other industries. The SparkEx Spark Detection and Extinguishing System is designed to detect hot particles, sparks and glowing embers that might become the igni-tion source for a fire or explosion if allowed to travel on through pneumatic ducting and conveyors towards other material handling equipment.
By preventing sparks, embers and hot particles from reaching dust rich down-stream process equipment such as dust collectors, bins and silos, both fire and explo-sion risks can be managed.
Using infrared detectors, the system detects the radiated light emitted from sparks, glowing embers and hot particles travelling past the detection point and acti-vates control circuits. The greatest sensitivity occurs when these sensors are employed in a dark area such as closed ductwork, although optional daylight detectors are also available for use on open conveyor belts and for applications where light is likely to be visible. Upon detection this system provides several options to manage the ignition risk:
• An electrical signal generated by the sensor activates control circuits typically used to operate an automatic water-extinguishing curtain. Sparks can be extinguished without stopping production.
• An automated shut down of the process can prevent the feed of combustible material.
• Alarm and control systems can be activated upon the detection of hot particles for other control devices such as diverter valves.The system detectors and control unit
are ATEX certified for use in a dusty work-ing environment. This means there are no expensive costs for additional wiring to run from detectors to remote mounted control units and plant personnel have direct access to the status of the equipment. In the event of an alarm condition, the operator can see immediately which process is at risk. A web based monitoring system, which allows plant managers to receive system alarms and faults to their smart phones, as well as monitor-ing the systems live on the internet, is also available.
In addition to this preventative sys-tem, systems for protection are available, should an explosion occur. A chemical isolation system isolates an explosion and prevents it from affecting interconnected
processes. If unprotected, the ductwork and piping, as well as all the connected vessels and equipment are at risk. This system is used in combination with explo-sion protection equipment on each vessel,
bin, or dust collector and could include chemical suppression, explosion venting or indoor venting.
Regulations, codes and standardsBecause of potential health problems,
laws exist to ensure employers in the EU protect their workers from being harmed by dangerous substances in the work-place. In the UK, under the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR), all work-places where substances that could give rise to fire or explosion are handled or stored must be fully assessed and protected.
Employers must carry out risk assessments, and take steps to ensure they prevent or adequately con-trol exposure. It is important to include in the assessment foreseeable inci-dents and main-tenance work and plan for measures to be taken in these circumstances.
ATEX is the name com-monly given to Directive 94/9/EC which pro-vides the techni-cal requirements to be applied and the relevant conformity assessment pro-cedures before placing equip-
ment and protective systems intended for use in potentially explosive atmospheres on the European market.
By investing in explosion protection, organisations can safeguard themselves eco-
nomically, follow appropriate health and safety standards and protect workers from potential risks.
More InforMatIon:BS&B Safety SystemsTel: +44 161 955 4202Email: [email protected]: www.bsbipd.com
Grain&feed millinG technoloGy January - february 2013 | 11
FEATURE
Bespoke systems My organisation, BS&B Safety Systems,
has launched a bespoke combustible dust fire and explosion prevention system for hammer mills based on established systems developed for other industries. The SparkEx Spark Detection and Extinguishing System is designed to detect hot particles, sparks and glowing embers that might become the igni-tion source for a fire or explosion if allowed to travel on through pneumatic ducting and conveyors towards other material handling equipment.
By preventing sparks, embers and hot particles from reaching dust rich down-stream process equipment such as dust collectors, bins and silos, both fire and explo-sion risks can be managed.
Using infrared detectors, the system detects the radiated light emitted from sparks, glowing embers and hot particles travelling past the detection point and acti-vates control circuits. The greatest sensitivity occurs when these sensors are employed in a dark area such as closed ductwork, although optional daylight detectors are also available for use on open conveyor belts and for applications where light is likely to be visible. Upon detection this system provides several options to manage the ignition risk:
• An electrical signal generated by the sensor activates control circuits typically used to operate an automatic water-extinguishing curtain. Sparks can be extinguished without stopping production.
• An automated shut down of the process can prevent the feed of combustible material.
• Alarm and control systems can be activated upon the detection of hot particles for other control devices such as diverter valves.The system detectors and control unit
are ATEX certified for use in a dusty work-ing environment. This means there are no expensive costs for additional wiring to run from detectors to remote mounted control units and plant personnel have direct access to the status of the equipment. In the event of an alarm condition, the operator can see immediately which process is at risk. A web based monitoring system, which allows plant managers to receive system alarms and faults to their smart phones, as well as monitor-ing the systems live on the internet, is also available.
In addition to this preventative sys-tem, systems for protection are available, should an explosion occur. A chemical isolation system isolates an explosion and prevents it from affecting interconnected
processes. If unprotected, the ductwork and piping, as well as all the connected vessels and equipment are at risk. This system is used in combination with explo-sion protection equipment on each vessel,
bin, or dust collector and could include chemical suppression, explosion venting or indoor venting.
Regulations, codes and standardsBecause of potential health problems,
laws exist to ensure employers in the EU protect their workers from being harmed by dangerous substances in the work-place. In the UK, under the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR), all work-places where substances that could give rise to fire or explosion are handled or stored must be fully assessed and protected.
Employers must carry out risk assessments, and take steps to ensure they prevent or adequately con-trol exposure. It is important to include in the assessment foreseeable inci-dents and main-tenance work and plan for measures to be taken in these circumstances.
ATEX is the name com-monly given to Directive 94/9/EC which pro-vides the techni-cal requirements to be applied and the relevant conformity assessment pro-cedures before placing equip-
ment and protective systems intended for use in potentially explosive atmospheres on the European market.
By investing in explosion protection, organisations can safeguard themselves eco-
nomically, follow appropriate health and safety standards and protect workers from potential risks.
More InforMatIon:BS&B Safety SystemsTel: +44 161 955 4202Email: [email protected]: www.bsbipd.com
Grain&feed millinG technoloGy January - february 2013 | 11
FEATURE
www.gfmt.co.uk
LINKS• Seethefullissue• VisittheGFMTwebsite
• ContacttheGFMTTeam
• SubscribetoGFMT
A subscription magazine for the global flour & feed milling industries - first published in 1891INCORPORATING PORTS, DISTRIBUTION AND FORMULATION
In this issue:
• Efficient barge unloading technology
• Feed enzymes in animal nutrition
• Controlling the explosion risks within hammer mills
• Use of computer programming in animal diet formulation
• Recycling surplus factory food into quality animal feeds
Janu
ary
- Feb
ruar
y 20
13
first published in 1891
ThisdigitalRe-printispartoftheJanuary|February2013editionofGrain&FeedMillingTechnologymagazine.Contentfromthemagazineisavailabletoviewfree-of-charge,bothasafullonlinemagazineonourwebsite,andasanarchiveofindividualfeaturesonthedocstocwebsite.Pleaseclickheretoviewourotherpublicationsonwww.docstoc.com.
Topurchaseapapercopyofthemagazine,ortosubscribetothepaperedi-tionpleasecontactourCirculationandSubscriptionsManageronthelinkadove.
INFORMATIONFORADVERTISERS-CLICKHERE
Article reprintsAll Grain & Feed Milling Tecchnology feature articles can be re-printed as a 4 or 8 page booklets (these have been used as point of sale materials, promotional materials for shows and exhibitions etc).
If you are interested in getting this article re-printed please contact the GFMT team for more informa-tion on - Tel: +44 1242 267707 - Email: [email protected] or visit www.gfmt.co.uk/reprints