PRB Fuel Yard Electrical System Best Practices · ROBERTS & SCHAEFER COMPANY Baltimore, MD. PRB...

PRB Fuel Yard - Electrical System Best Practices

PRB Fuel Yard Electrical SystemBest Practices

Presented by:Mark CollettRay GundersenROBERTS & SCHAEFER COMPANY

Baltimore, MD


HOW THE WORLD PROCESSES ITS RESOURCES

since 1903ROBERTS & SCHAEFER COMPANY

ENGINEERING & CONSTRUCTION SERVICES


100 years of Fuel Yard Design Expertise

•100 years of service to the industry

•Diversity from other industries

•Revenue exceeding $1.25 billion in design & construction

Mine to Boiler!


Fuel Yard Audits and PRB Conversions

Audits for Conversion• Adjustments in Layout• Addition of Covered Storage• Dust Control Improvement• Fire Protection• Automatic Washdown


Largest installed base of PRB Coal Mining Facilities

COLORADOTrapperSenecaEmpireTwenty MileBearBowieWest ElkNew HorizonKingSommerset

MONTANARosebudBig SkySpring CreekDeckerBig Horn

WYOMINGBuckskinEagle ButteRawhideDry ForkWyodakCaballoBelle AyrCaballo RojoCorderoCoal CreekJacobs RanchBlack ThunderNorth AntelopeRochelleNorth RochelleAntelopeDave JohnstonShoshoneMedicine BowJim BridgerBlack ButteKemmerer

UTAHSoldier CreekWhite OakWillow CreekSkylineCentennialPlateauCrandall CanyonDeer CreekCottonwoodSUFCODugout

ARIZONA/NEW MEXICOKayentaBlack MesaMcKinnleyNavajoSan JuanLee RanchYorkLa Platta


Passive Truck Dumps and Overland Belts bring Mining Operations Efficiency to PRB


100 yrs in Transportation & Facility Loading / Unloading Logistics


Presentation Objectives

• State the Objectives of PRBCUG Electrical Best Practices

• Contributors

• Status & Plan

• Review Format & Table of Contents

• Discuss the Philosophy

• Open Discussion of Sections & Issues


Objectives

“The intellect has a sharp eye for

methods and tools, but is blind to

ends and values”.

Albert Einstein


PRB COAL USERS GROUP - Objectives

The PRB Coal Users’ Group was formed to promote the safe, efficient and environmental use of Powder River Basin (PRB) Coals by electric generating companies that currently use, or are considering using, PRB coals.–Establish best practices for the safe operation

and maintenance systems for …–Forum and Database–Annually select PRB Coal Plant of the Year–Cooperate with other industry groups


Best Practice Objectives

• Clarify practices which support codes and standards.

• Introduce (with reference to applicable codes) practices and techniques which have been proven to improve operations & maintenance safety or mitigate capital expenditures without violating these codes.


Contributors

• Mark Collett, E.E., Roberts & Schaefer Company - FACILITATOR– PRBCUG Board of Directors

• Ray Gundersen, P.E., E.E., Roberts & Schaefer Company– Sr. Electrical Engineer & Project Engineer

• Daryle Orbeck - Daryles Electric - Gillette, WY– Principal– Code Instructor

• Occupational Saftey and Health Administration (OSHA)– New Construction & Retrofit / Conversions group WILL NOT

approve, certify, or endorse any best practice.– Regional OSHA personnel are willing to comment

• Bill Rezek, P.E., E.E., - Bechtel Power Corporation– Sr. Electrical Engineer


Status & Plan

•First Draft Completed•Several Issues Flagged

–Dual Rating of Devices (CI D2 & CII D1)–Washdown water migration vs. Explosion Proof Device seals–Realistic Methane standards and mitigation requirements

•Each Issue will be Assigned•Second Review

–Issue cross assigned•Final Review•Issue for Approval•Submission on web-site•Presentation Chicago 2005

Raintight is not Watertight


Approach & Table of Contents Review

1.0 Introduction2.0 Scope3.0 Application of Building Codes and Federal Standards4.0 Electrical Devices & Equipment in PRB Coal Handling Systems5.0 Design & Specification of Electrical Devices & Equipment6.0 Construction & Implementation7.0 Operations & Maintenance8.0 Ignition & Emergencies9.0 Summary10. References11. Appendix


Discuss the Philosophy

• Understand Sources of Ignition, Determine Area Classifications w/Consultant & Local Authority

• Mitigate where appropriate to allow less $ equipment.

• Adopt other best practices in design, construction, operations, & maintenance.

• Remain committed to standards and mitigations.


Open Discussion of Sections & Issues

3.0 Application of Building Codes and Federal Standards4.0 Electrical Devices & Equipment in PRB Coal Handling Systems5.0 Design & Specification of Electrical Devices & Equipment6.0 Construction & Implementation7.0 Operations & Maintenance8.0 Ignition & Emergencies


Area Classification Drawing and supporting documentation to show approach.

Process of mitigation in Petrochem Industry is “HAZOPP Review”


Applicable Building Codes and Federal Std’s Every classification requires Class, Div, Group

ClassesClass I Hazardous because flammable gases or vapors are present in

the air in quantities sufficient to produce explosive or ignitable mixtures.

Class II Hazardous because combustible or conductive dusts are present

Class III Hazardous because ignitable fibers or flyings are present, but not likely to be in suspension in sufficient quantities to produce ignitable mixtures.

Divisions The division defines the probability of hazardous material being present in an ignitable concentration in the surrounding atmosphere.

Division 1 The substance referred to by class is present during normal conditions.

Division 2 The substance referred to by class is present only in abnormal conditions, such as a container failure or system breakdown.


Applicable Building Codes and Federal Std’s

Groups

The group defines the hazardous material in the surrounding atmosphere.

Group A Acetylene

Group B Hydrogen, fuel and combustible process gases containing more than 30% hydrogen by volume or gases of equivalent hazard such as butadiene, ethylene, oxide, propylene oxide and acrolein.

Group C Ethyl and ethylene or gases of equivalent hazard.

Group D Gasoline, acetone, ammonia, benzene, butane, cyclopropane, ethanol, hexane, methanol, methane, natural gas, naphtha, propane or gases of equivalent hazard.

Group E Combustible metal dusts, including aluminum, magnesium and their commercial alloys or other combustible dusts whose particle size, abrasiveness and conductivity present similar hazards in connection with electrical equipment.

Group F Carbonaceous dusts, coal black, charcoal, coal or coke dusts that have more than 8% total entrapped volatiles or dusts that have been sesitized by other material so they present an explosion hazard.

Group G Flour dust, grain, wood, plastic and chemicals.


Other Codes and Exclusions

Other Codes• “ZONEPHOBIA” with new European Union Zone Based Classifications

(similar but different) KEEP CURRENT!!!• Factory Mutual (FM)• CSA (Canadian Standards Association)• Underwriters Labs (UL) Certification

Exclusions• Power Plants not covered by MSHA or NEC. But, default to NEC.


Enforcement and Jurisdictions

WHO CARES?

• Owner - Safety, capital cost of repairs, and down-time. Especially true of large, self insured facilities.

• Insurer - Understand their expectations (do you know who they are)? Some companies have gone to MSHA standards to satisfy insurers, even though MSHA has no jurisdiction (mine to mouth battles).

• Federal OSHA inspectors…to THEIR interpretation.

• Local State, City and County inspectors look at building code compliance and NEC (adopted).


Critical Areas to be addressed by the final Best Practices Document• Rail Delivery and Dump Hopper

• Open Conveyor Trusses

• Closed Conveyor Trusses or Galleries

• Screening and Crushing

• Outside Storage

• Inside Storage or Silos

• Tripper Deck

• Pulverizing / Grinding


Sources of Ignition

Explosion = +Source of Energy+Flammable gases or dusts+Proper proportion of air

NEMA DEVICESIgnition CapableTemperature RatedWater Resistant

MITIGATION ofMethane and 40 mesh or smallerCoal Dust

HIGHER CLASSIFICATIONS=MORE CAPITAL


NEMA Devices - Ignition Capable

Ignition Capable (arcing, sparking)• Switches (pull chord, level switch, rip detect, etc.)• Breakers or Starters• Plugs or Receptacles• Pushbutton Stations


NEMA Devices - Understanding Environments

• Indoors / Outdoors• Water -- Drip / Rain / Hose / Submersion / Ice• Dust -- Settling, Circulating, or Windblown Dust• Corrosive Liquids / Oil / Noncorrosive Liquids• Hazardous Location -- Gas / Combustible Dust


NEMA Devices - Common to all Enclosures

Provide A Degree Of Protection To Personnel Against Incidental Contact With The Enclosed Equipment


NEMA Devices - Definitions

• Driptight -– Falling dirt or moisture will not enter the enclosure

• Dusttight or Dust-Ignition Proof– Circulating or airborne dust will not enter the enclosure

• Rainproof -– Exposure to beating rain will not interfere with the operation of the

apparatus or result in wetting of live parts and wiring within the enclosure

• Raintight -– Exposure to beating rain will not result in entrance of water

• Watertight -– Water will not enter enclosure when subjected to a stream of water


NEMA Devices - Enclosure Types

Type 1• Indoor Use• General Purpose (Not Exposed To

Unusual Conditions)• Degree of Protection From Falling

Dirt



• Indoor Use• Degree Of Protection From:

• Falling Dirt• Dripping Non-Corrosive

Liquid• Light Splashing of Non-

Corrosive Liquid

Type 2



• Indoor or Outdoor Use• Degree of Protection From:

• Falling Dirt, Rain, Sleet, and Snow• Windblown Dust

• Undamaged by the External Formation of Ice.

Type 3




• Falling Dirt, Rain, Sleet, and Snow

• Not Dustproof, Snowproof, or Sleetproof

• Undamaged by the External Formation of Ice

Type 3R



Type 3S• Indoor or Outdoor Use• Degree of Protection From:

• Falling Dirt, Rain, Sleet, Snow, and Windblown Dust

• External Mechanism(s) remain Operable When Ice Laden




• Windblown Dust and Rain• Splashing Water• Hose Directed Water***• Undamaged by the External

Formation of Ice

Type 4***



• Windblown Dust and Rain• Splashing Water• Hose Directed Water***• Damage from External Ice

Formation• Corrosion Resistive


Type 4X*** NOT 4X



Type 5• Indoor Use• Degree of Protection From:

– Falling Dirt, Settling Airborne Dust, Lint, Fibers, and Flyings

– Dripping and Light Splashing of Noncorrosive Liquids



Type 6• Indoor or Outdoor Use• Degree of Protection From:

– Falling Dirt– Hose Directed Water– Damage From External Ice

Formation– Entry of Water During Occasional

Temporary Submersion at a Limited Depth



Type 6P• Indoor or Outdoor Use• Degree of Protection From:

– Falling Dirt– Hose Directed Water– Damage From External Ice Formation– Entry of Water During Prolonged Submersion at a

Limited Depth



• Indoor use in locations classified as Class I, Groups A, B, C, or D, as defined in the NEC.***

• Protection against Hazardous Location atmospheres containing Gases and Vapors. METHANE!!

• EXPENSIVE• WON’T PROTECT AGAINST

WASHDOWN WATER

Type 7***



Type 8• Indoor or Outdoor use in locations classified as Class

I, Groups A, B, C, or D, as defined in the the NEC.• Protection against Hazardous Location atmospheres

containing Gases and Vapors.• Arcing contacts, connections, … are immersed in oil

in order to confine ignition source.



• Indoor use in locations classified as Class II, Groups E, F, or G, as defined in the the NEC.***

• Protection against Hazardous Location atmospheres containing Dust.

• EXPENSIVE• WON’T PROTECT AGAINST WASHDOWN

WATER.

Type 9***

Not dustproof



Comparison of Indoor Enclosure ApplicationsEnclosure Type

Condition of Protection 1 2 4 4X 5 6 6P 12(K) 13Falling Dirt X X X X X X X X XFalling Liquids and Light Splashings -- X X X X X X X XCirculating dust, lint, fibers, & flyings -- -- X X -- X X X XSettling airborne dust, lint, fibers & flyings* -- -- X X X X X X XHosedown and Splashing water -- -- X X -- X X -- --Oil and Coolant seepage -- -- -- -- -- -- -- X XOil or Coolant spraying and splashing -- -- -- -- -- -- -- -- XCorrosive Agents -- -- -- X -- -- X -- --Occasional Temporary Submersion -- -- -- -- -- X X -- --Occasional Prolonged Submersion -- -- -- -- -- -- X -- --

* These fibers and flyings are nonhazardous materials and are not considered Class III type ignitable fibers or combustibles flyings Table: NEMA 250



Comparison of Outdoor Enclosure Applications

Enclosure TypeCondition of Protection 3 3R 3S 4 4XRain, snow, sleet X X X X XSleet (External Operating Mech. Operable w/ ice) -- -- X -- --Windblown dust X -- X X XHosedown -- -- -- X XCorrosive Agents -- -- -- -- X



Comparison of Indoor Enclosure Applications for Hazardous Locations Type 7 & 8 Type 9 Atmosphere Containing: Class A B C D E F G 10Acetylene I X -- -- -- -- -- -- --Hydrogen, manufactured gas I -- X -- -- -- -- -- --Diethel ether, ethylene, cyclopropane I -- -- X -- -- -- -- --Gasoline, hexane, butane, naphtha,

propane,acetone,toluene, isoprene I -- -- -- X -- -- -- --Metal dust II -- -- -- -- X -- -- --Carbon black, coal dust, coke dust II -- -- -- -- -- X -- --Flour, starch, grain dust II -- -- -- -- -- -- X --Fiber flyings III -- -- -- -- -- -- X --Methane with or without coal dust MSHA -- -- -- -- -- -- -- X

Table: NEMA 250

NFPA 496, Purged and Pressurized Enclosures ..., outlines alternatives to Type 7 & 9 Enclosures when adequate positive pressure ventilation is used.



Multiple Rated*** EnclosuresType 3, 3R, 4X, 5, 12

Stainless Steel or other materials approvedfor the use (Corrosion Protection)

Gasketing (Dust and Water Protection)

Drain Plug (Remove for Type 3R)



Ignition Capable (arcing, sparking)• Switches (pull chord, level switch, rip detect, etc.)• Breakers or Starters• Plugs or Receptacles• Pushbutton Stations

Dual Volatiles=Dual RatingNEMA 4/7/9

w/seals

Intrinsically Safe Equipment???


Construction & Implementation - Seals & Conduit


MITIGATING for CLASS I

Results of adequate Methane Detection, Alarm, & Power Interrupt?

From C1 D2 to non-classified for gasses & vapors. However, Methane Detection must be C1 D1.

RELIABILITY SUCKS


MITIGATING for CLASS II

Results of adequate Dust Control and Washdown?In some cases, from CI D1 to non-rated! NEMA 4


NEMA Devices - Temperature Rated

Temperature Rated Equipment• Lighting• Motors• Transformers

Temp. rated, labeled,w/seals

TotallyEnclosedFanCooled


NEMA Devices - Balance of Plant Enclosures

• NEMA 4 or 4X for Washdown / Water


Design & Specification - Best Practices

OR

Well thought out designs that minimize capital while enhancing safety and reliability.– Control & Distrubution

Areas located strategically


Construction & Implementation - Misc.

• Static Protection• Grounding• Conduit Entry• Conduit Expansion Joints• Conductor Supports on Vertical Runs• No multi-circuit branch circuits• Isolated neutrals• Positive Pressure


Operations & Maintenance

• COMMITMENT to your mitigation practices!!!


Operations & Maintenance

• Close up devices and enclosures.

• New de-energization code guidelines

• Keep a copy of the Area Classification Drawing in every MCC and insure that it is followed for repairs, or new installations


Ignitions & Emergencies

• Bunker & Silo Fire Fighting Best Practice• Will have new references to Electrical Fire Fighting Resources• Housekeeping’s Mitigating Effect on Ancillary Fires

– Midwest plant hada fire in an ElectricalDistribution Roomadjacent to the Crusher House.No secondaryexplosion!!


Summary

• Determine Area Classifications with Local Authority• Worst Case Scenarios = CI D2 and CII D2 + washdown • Mitigate where appropriate to allow less expensive

equipment.– Ignition Capable

• Ventilation + Monitoring/Trip = No Class I rating?• Dust Control + Washdown = No Hazardous rating?

– Observe T Ratings for all Motors & Lighting + seals– Balance of Plant Enclosures = Nema 4 or 4X

• Adopt other best practices in design, construction, operations, & maintenance.

• Remain committed to standards and mitigations.

PRB Fuel Yard Electrical System Best Practices · ROBERTS & SCHAEFER COMPANY Baltimore, MD. PRB...

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Transcript of PRB Fuel Yard Electrical System Best Practices · ROBERTS & SCHAEFER COMPANY Baltimore, MD. PRB...