(another one fights the) dust

(Another One Fights the) Dusta.k.a. Identifying and Managing Combustible Dust Hazards in Your Distillery

Devin Mills (Dalkita) & Colleen Moore (Dalkita)

DEVIN MILLS DISTILLERY ENGINEER

§ Process Planning§ Equipment Planning§ Licensed Professional Engineer§ MBA – University of Colorado, Boulder§ B.S. Petroleum Engineering – Colorado School of

Mines§ Host Distilling Craft Podcast

EXPLOSABLE DUSTSmaller than 500 µm (0.5mm)§ Pass through 35 mesh screen§ Long skinny particles can also count

Sieve # Mesh (mm) Fraction Mash tun Lauter tun Mash Filter1 1.27 Husk 27% 18-25% 8-12%2 0.26 Coarse grits 9% 8-<10% 3-6%3 0.15 Fine grits I 24% 35% 15-25%4 0.07 Fine grits II 18% 21% 35-45%5 0.04 Flour 14% 7% 8-11%

Tray - Fine flour 8% 11-<15% 12-18%

CHARACTERISTICSRequires the ability to burn§ Dry§ Correct materials

:_(

§ Grain qualifies§ So does metal§ Fiberglass, non-dairy creamer§ Dirt doesn’t qualify

def·la·gra·tion/ˌdefləˈɡrāSH(ə)n/noun

the action of heating a substance until it burns away rapidly.§ technical

combustion that propagates through a gas or across the surface of an explosive at subsonic speeds, driven by the transfer of heat.

http://www.youtube.com/watch?v=NlE9ZRNe2Z4

A high-speed recording of a demonstration simulating what happens when a spark occurs inside a grain silo or flour mill. Regular flour and a match.

DO YOU HAVE IT?Sampling Plan§ Need 2 pounds to properly test§ Density of grain dust is 35-40 lb/ft3

§ Collect samples near where to mill or use grain§ NEC uses 20’ and 30’ borders for Dust Hazard boundaries.

§ Put samples in a sealed bag

DO YOU HAVE IT?§ Sampling plan§ Grab samples near where to mill or use grain§ NEC uses 20’ and 30’ borders for Dust Hazard boundaries.

§ Need 2 pound to properly test§ Density of grain dust is 35-40 lb/ft3

Table 1: Go/No Go Explosibility Screening Test ResultsMaterial: Dust BlendRoom Temperature: 20°CRelative Humidity: 55%

Barometric Pressure: 991 mbarDate of Test: 8/31/15

Moisture Content (wt.%)

Mean Particle Size (µm)

1.2-L Hartmann 20-L Chamber

Volume (ml)Explosible(Yes/No)

Dust Concentration Tested (g/m3)

ExplosionOverpressure

(bar)Explosible(Yes/No)

3.9 3297% < 75 µm 5 Yes n/a n/a n/a

DO YOU HAVE IT?§ Sampling plan§ Grab samples near where to mill or use grain§ NEC uses 20’ and 30’ borders for Dust Hazard boundaries.

§ Need 2 pound to properly test§ Density of grain dust is 35-40 lb/ft3

Table 2: Combustibility Screening Test ResultsRoom Temperature: 20°CRelative Humidity: 58%

Barometric Pressure: 992 mbarDate of Test: 8/31/15

MaterialTime to Ignition

(see) Combustion Classification Observations

Dust Blend 5 CL-3

-Localized combustion after ignition source was removed-No propagation observed

WHERE IS IT?Sources§ Whole grain§ Pre-milled grain§ Flaked grain§ Dextrose powder§ Sugar 10x

INSIDE YOUR STORAGE ROOM…§ Combustible material needs to be isolated from other storage

13.10 Miscellaneous Storage in Grain-Handling Facilities.

13.10.1 Sacks, nonessential uninstalled machinery or parts, or other supplies shall not be stored in areas where the only other combustible material is the agricultural commodity that is being stored.

INSIDE YOUR MILL ROOM…7.5.2.5 Dry milling or grinding of starch shall be performed in a separate buildingwith explosion relief or in a separate building with explosion relief or in a separateroom isolated from other areas by interior walls designed according to 4.1.2.

Exception No. 1 This requirement shall not apply if the equipment can bedesigned to be protected in accordance with NFPA 69, Standard onExplosion Prevention Systems, by deflagration containment, by explosionsuppression, or by inerting the volume to reduce oxygen such thatcombustion is not supported.

Exception No. 2: This requirement shall not apply if mills are providedwith explosion venting to a safe outside location. If explosion vent ductslonger than 3 m (10 ft) are to be used, the milling equipment andexplosion vent duct shall be designed to withstand the increased ventedexplosion pressure.

WHERE IS THE DUST?

HYBRID MIXTURES§ Very important to keep dust and booze separate!§NFPA 652:

§ How much is that?§ Ethanol – 0.33%§ Dust – 6 g/m3

MINIMUM EXPLOSIVE CONTENT

How much dust is that? 1/100” in 8’ ceiling

Table A.5.2.2(a) 20-L Sphere Test Data – Agricultural Dusts

Dust NamePmax

(bar g)

(1)KSt

(bar m/sec)Percent

MoistureParticle Size

(µm)

Minimum Explosive

Concentration (g/m3)

Percent Greater Than

200 Mesh

Corn Meal 6.2 47 8.2 403Potato Flour 9.1 69 65 125Rice Dust 7.7 118 2.5 4Wheat Grain Dust 9.3 112 80 60Sugar (10x) 8.4 154Malt 7.5 170 10.5 72Rye Flour 8.9 79 29

NFPA 69

10 Sheets of Paper

THE IGNITION SOURCE§ Static electricity§ Lightening§Non-rated equipment§ Hot Surfaces§ Sparks§Open Flames

DUST HAZARD ANALYSIS (DHA)§ Determine current problems§ Determine solutions§ Implementation plan

DUST HAZARD ANALYSIS (DHA)§ Required in all facilities by Sep 7, 2018 (2016 NFPA 652)

7.1.2.1 For existing processes and facility compartments that are undergoingmaterial modification, the owner/operator shall complete DHAs as part of theproject.

7.1.2.2* For existing processes and facility compartments that are notundergoing material modification, the owner/operator shall schedule andcomplete DHAs of existing processes and facility compartments within 3-year period from the effective date of the standard. The owner/operator shalldemonstrate reasonable progress in each of the 3 years.

SOLUTION: ELIMINATE THE DUST

§Housekeeping Plan (Cleaning Schedule)§Remove Dust from System/Process§Room Design

HOUSEKEEPING PLAN

General Principle: If there is no dust, it can’t explode.

Housekeeping Schedule

Level of Accumulation When to CleanFugitive Emissions No More than AnnuallyNormal Operations 24 Hours

Spills between 1/100” and 1/8 “ 1 HourSpills > than 1/8 “ Immediately

1/8” = 2 quarters stacked together

WAYS NOT TO CLEAN

Spreading the combustible dust around and making it airborne actually increases your chances of a combustible dust explosion.

WAYS TO CLEAN§Wet Rag§Mop§ Sweeping *§ Flagged/frayed and flexible bristles§ Keep the dust down

§ Vacuum *§ Class II /Div 1/Hazard Group G

* Indicates additional guidelines or regulations apply

sad beep

VACUUMS

XOXO ~ NEC 499:3.3.4.3

WTF… AN $8-12K VACUUM!?!§ Depends on amount of dust.

§ Housekeeping Plan call for a vacuum?

§ Vacuums – with electric motors and metal parts – could produce a dangerous spark.

§ Specialized industrial vacuums are an easy way to combat combustible dust.

REMOVE FROM SYSTEM§ Is this even possible in your process?§ Ex: Using molasses instead of sugar

§Not an option for a lot of distillers with established product lines

ROOM DESIGN§ Paint§ High gloss§ Color easy to see dust

§ No surfaces under 60°§ Ceiling beams and joists§ Dangling lights§ Shelves

§ No hidden compartments§ Drop ceiling§ Non-dust tight compartments§ Recessed lighting§ Equipment panels

§ Raise equipment off floor§ Either dust tight to floor or easy

to see if sweeping/vacuuming effective

ELIMINATE OXYGEN§One Leg of the Dust Pentagon§Nitrogen blanket/ Nitrogen inerting§ Can be Dangerous to Personnel

Questions?Seriously… don’t make this weird.

POP QUIZ

How do combustible dust explosions happen?

POP QUIZ

Fire Triangle +

Dispersion + Confinement

POP QUIZFuel to burn + Oxygen + Ignition source

A dust explosion needs two additional elements:

DispersionDust particles suspended in air, in the right concentration.

ConfinementDust cloud is in an enclosed or limited space. This restriction allows pressure to build up,

increasing the likelihood of an explosion.

THANK YOU!Colleen Moore & Devin Mills

Dalkita Architecture & Construction303.765.1295 x101

colleen@dalkita.com