INCINERATION. Combustion Efficiency. NACT Incinerators NACT 270. Incinerators. 3 T's Time (of residence) Temperature Turbulence

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1 NACT 270 Incinerators INCINERATION A combustion process, in which the primary purpose is to destroy combustible material. Biomedical Incinerators: Hospital, Pathological and Crematory Incinerators. Heat Stripping Ovens Combustion Efficiency 3 T's Time (of residence) Temperature Turbulence 1

2 Combustion Stoichiometric Combustion Excess Air Combustion Substoichiometric Combustion Solid Waste Incinerators Open Burning Open-Pit Incinerators Teepee Burners Single Chamber Incinerators Multiple Chamber Incinerators Controlled Air Incinerators Rotary Kiln Incinerators Stack Combustion Chamber Refractory Waste Grate Ash Pit Overfire Air Ports Charge Door Auxiliary Fuel Underfire Air Ports Ash Removal Door Single Chamber Incinerator 2

3 Controlled-Air Incinerator with Staged Hearth and Automatic Ash Removal To Stack or Boiler Secondary Chamber Secondary Burner Primary Burner Feed Ram Ash Transfer Rams Ash Sump Ash Discharge Ram Ash Chute Ash Quench Al Stages Rams 3

4 Controlled Air Incinerator Components Stack Control Panel Secondary Chamber View Port Secondary Burner Secondary Combustion Air Blower Mechanical Charge System View Port Ash Removal Door Primary Burner Primary Chamber Primary Combustion Air Burner Blower Secondary Primary Blower 4

5 AFTERBURNER In-line Multiple- Chamber Incinerator (Excess-Air) Charging Door Ignition Chamber Flame Port Secondary Air Port Curtain Wall Secondary Combustion Chamber Grates Cleanout Doors Location of Secondary Burner Mixing Chamber Clean Out Doors Curtain Wall Port Retort Multiple Chamber Incinerator Flame Port Stack Charging Door Secondary Air Ports Ignition Chamber Secondary Burner Port Mixing Chamber Hearth First Underhearth Port 5

6 Flame Port 6

7 HOPPER-RAM Waste Charging Hopper Hydraulic Fire Door Actuator Fire Door Hopper Cover Primary Combustion Chamber Hydraulic Ram Actuator Ram Face Quench Spray Charging Ram Furnace Opening IIA Waste Classification TYPES 0-8 Vary by Composition Vary by Moisture Content Vary by Btu value per pound fired 7

8 Type 0 - Trash Highly Combustible Waste such as paper, wood, plastic or rubber 10% Moisture Content 8,500 Btu per pound, as fired Type 1 - Rubbish Combustible waste such as paper, rags, wood scraps, domestic, commercial, industrial sources 25% moisture content 6,500 Btu per pound, as fired Type 2 - Refuse Rubbish and garbage, residential sources 50% moisture content 4,300 Btu per pound, as fired 8

9 Type 3 - Garbage Animal and vegetable wastes, restaurants, hotels, markets, institutional sources 70% moisture content 2,500 Btu per pound, as fired Type 4 Animal Solids, Organic Wastes Carcasses, organs, solid organic wastes, hospital, lab, animal pounds 85% moisture content 1000 Btu per pound, as fired Type 5 Gaseous, Liquid, or Semi-Solid Wastes Industrial Process by-product wastes such as tar, paint, solvents, sludge, fumes Moisture content depends on components Btu values variable 9

10 Type 6 Semi-solid, Solid Wastes Industrial by-product combustibles such as rubber, plastics, and wood waste Moisture content variable Btu values variable Type 7 Medical Waste - Low Chlorine Content Medical Waste including red bag (regulated) and non-regulated. Includes waste from food service, administration, patient rooms,operating rooms, labs Btu per pound Type 8 Medical Waste - High Chlorine Content Medical Wastes, only red bag type (regulated) Includes Type 7 waste plus higher concentrations of lab wastes, chlorinated plastics, noncombustible solids Btu per pound 10

11 Modes of Operation Waste Charging Batch Intermittent Continuous Ash Removal Manual Automatic 11

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13 Quickset Insulation FRONT Insulating Block Cremation Burner Castable Roof Insulating Block Exhaust Gas Outlet Loading Door Afterburner Throat Air Jets Hearth Air Jets Castable Support Lintel Insulating Block Insulated Firebrick Rear Wall Divider Wall Refractory Lined Floor Insulating Block Insulating Block Cremation Hearth Castable support Arch CREMATOR 13

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15 Categories of Industrial Incinerators Volume Reduction (trash, wood, solid waste streams) Toxicity Reduction (any toxic waste stream) Resource Recovery (copper wire, steel drums, electric motors) Industrial Heat Cleaning (Burnout) Ovens Primary Chamber F Secondary Chamber F Roasting Condition in Primary Low Oxygen Environment Volatiles & Smoke go to Afterburner Water Mist Injection in Primary 15

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17 Typical Incinerator Operating Procedures Before Start-up Start-up Charging/Burning Burn Down Shutdown (batch & intermittent) 17

18 Before Incinerator Start-up Manual Ash Removal Automatic Ash Removal Routine Daily Inspection Burner & Blower Check Typical Incinerator Operating Procedures Operating Step Typical Duration 1. Ash Cleanout 15 to 30 minutes 2. Pre-Heat 15 to 60 minutes 3. Charging & Burning Up to 14 hours 4. Burndown 2 to 4 hours 5. Cooldown 5 to 8 hours Incinerator Operation Waste Logging Pre- Heating Charging 18

19 Shutdown Batch or Intermittent Duty: Combustion Blowers left on to cool Typically lasts 5 to 8 hours Ash removed and inspected Typical Operational Errors Charging before Operating Temps. Are Achieved (failure to Pre-heat) Overcharging Waste with Excessive Moisture Incinerator Emissions & Control 19

20 Emissions Visible Emissions (Stack or Fugitive) Particulate Matter (Concentration/Weight) Acid Gases (NOx, SOx, HCl) Toxics (Dioxins, Furans, Heavy Metals) Pollutant Formation Factors Fuel Composition Charging Method and Rate Incinerator Type and Design Combustion Conditions (3 T's) Excess Air Incinerator Emissions Control Source Separation Combustion Control Flue Gas Controls (APC equipment) 20

21 Particulate Matter Formation Suspension of Inorganic Substances Incomplete Combustion of Fuel Materials Condensation of Vaporous Metals Smoke Formation Black Smoke Too Little Oxygen Relative to Fuel Usually Caused by Overcharging White Smoke Premature Cooling of Flue Gas Excessive Air Inorganic Particles Malfunction in Stack Damper or Fan Burner Overfired Too Much Highly Volatile Waste Temp. Too High Adjust Ash Ram Discharge Cycle Too Much Underfire Primary Air "POSITIVE" CONDITION - SMOKE LEAKING 21

22 Poor Mixing Too Much Highly Volatile Waste Burner Failure, Temperature too Low Not Enough Secondary Air BLACK SMOKE (Incomplete Burning - Soot Formation) Too Much Underfire Air Secondary Chamber Temperature Too Low Problem Waste Material Too Much Secondary Air Too Much Underfire Air WHITE/BLUE SMOKE Visible Fly Ash Air Infiltration Flame Port Air Problem Wastes High Primary Temperature Excessive Underfire Air High Draft Too High 22

23 Carbon Monoxide Formation Insufficient Oxygen for Complete Combustion Indicator of Inadequate Combustion Air Turbulence Indicator of Combustion Efficiency Products of Incomplete Combustion (PIC s) Greater Combustion Efficiency = Lower Dioxins Can occur when charging PVC plastics Dioxins are some of the most toxic manmade substances Polycyclic Aromatic Hydrocarbons (PAH s) Polychlorinated Biphenyls (PCB s) Stack Monitoring Opacity Temperature Flow Rate Oxygen Carbon Monoxide 23

24 Wet Scrubbers Remove both Particulates & Acid Gases Rely on Flue Gas Pressure Drop for Particulate Removal with Alkali Reagent for Acid Gas Removal. Categories of scrubbers: Spray Chambers Packed Towers (Beds) Venturi Wet Scrubber Acid Gas Removal Sodium Hydroxide (NaOH - Caustic Soda) or Sodium Carbonate (Na 2 CO 3 ) Alkali Added to Re-circulation Tank Water (ph of 8-9). 24

25 Spray Tower, Countercurrent-Flow Type Clean Exhaust Gas Liquid Sprays Dirty Flue Gas Water Drain Spray Tower Blower Motor Filtration & Pumps Common Spray Tower Scrubber Problems Liquor spray nozzles plugged Erosion of spray nozzles Corrosion of shell Mist re-entrainment 25

26 Clean Exhaust Shell Mist Eliminator Liquid Sprays Packing Dirty Exhaust Countercurrent- Flow Packed-Bed Scrubber Liquor inlet PACKED BED SCRUBBER Exhaust Gas Inlet Packed-Bed Operating Problems Accumulation of Solids Settling of Packing Material Liquor ph (between ) 26

27 Liquid Inlet SPRAY VENTURI WITH RECTANGULAR THROAT Particle Behavior in Venturi-Scrubber Section Flue-Gas Inlet from Quench Particles Accelerate Converging Region Particles collide with droplets Droplets have no axial velocity Throat Spray Nozzle Particles Decelerate Droplets Accelerate Diverging Region Flue-Gas Outlet to Separator Tower Section Liquor Flow Exhaust Gas Flow 27

28 Incinerator Inspection Inspector Safety Equipment Hard hat Safety glasses or goggles Gloves Steel-tipped safety shoes Ear protectors Agency safety policy Identify Potential Safety Problems Eye Injuries: Watching flames through hatches Scrubber liquor Sharps & Infectious Wastes: Avoid skin contact Burns: Contact with hot equipment Inhalation Hazards: Fugitive leaks, high-pressure scrubbers, ducts Alkaline reagent storage/mixing equip Stacks or vents 28

29 Common Potential Safety Problems Weak or Slippery Walkways/Ladders Corroded Ductwork or Control Devices High Electrical Voltage, Control Cabinets Rotating Equipment: Fans/Fan Belts Air Pollution Control Points of Inspection Capture Transport Air Mover Instrumentation Control Subsystem 29

30 Capture Are Emissions immediately Drawn into a control Device? Collection device Hoods Transport Are Emissions Moved to the Control Device Without Loss Are There any Leaks 30

31 Air Mover Is the fan big enough for the Job? Is it Operating as Designed and Permitted? 31

32 Horsepower? Instrumentation Are the proper instruments present? Do these instruments appear to be functioning? Are the instruments showing the appropriate units? 32

33 Scrubber Pressure Drop ph Meter Control Device Is it On? Visible Emissions? 33

34 Subsystem What is the Ultimate Fate of the Captured Emissions? 34

35 What about Violations? Notice To Comply (NTC) Minor deficiency Non-emissions related Non-recurring What about Violations? Notice Of Violation (NOV) Emissions related Same problem at last inspection 35

36 Four Options After A NOV Continue to operate in violation Cease the non-compliant activity (shut down the operation) Correct the problem Apply for a variance (if allowed) Incinerator Regulatory Requirements Regulatory Requirements General Air Emissions Limitations Visible Emissions Particulate Matter Fugitive Dust Gaseous Emissions Toxic Emissions Permit to Operate Conditions 36

37 Incinerator Rules Term Definitions Acceptable Incinerator Multiple Chamber Combustible Refuse Rubbish Incinerator Particulate Emissions Rules Burning > 100 pounds per hour = < 0.10 grains/cubic foot. Burning < 100 pounds per hour = < 0.30 grains/cubic foot. No Particulate Matter > 0.10 pounds per 100 pounds of waste charged. Prohibit "particles which are large enough to be visible in the atmosphere" SOx and NOx Emissions Limits SOx - Rule may limit 2% by volume of sulfur dioxide, calculated over 15 consecutive minutes. NOx - Typically not applicable to small incinerators. 37

38 EPA New Source Performance Standards Clean Air Act Amendments of 1990 required EPA to develop Emission Guidelines (EG s) for: Municipal Waste Combustors Medical Waste Incinerators Industrial and Commercial Waste Incinerators Other Solid Waste Incinerators EG s exist for Municipal Waste Combustors and Hospital/Medical/Infectious Waste Incinerators Permit Conditions: Equipment requirements Operating conditions Monitoring and recording Compliance testing Operation and maintenance manual Operator training Equipment Requirements Approved incinerator type, burners, fans, ductwork, etc. Properly Maintained Approved capture and control device 38

39 Incinerator Operating Conditions Pre-Heat Temperature primary chamber preheated to F prior to charging. Secondary chamber preheated F. Operating Temperature Primary chamber about F. Secondary chamber within F. Incinerator Operating Conditions (Cont.) Limit flue-gas temperature Types of wastes charged Charging rates Ash removal Hours of operation Prevention of nuisance Monitoring and Record keeping May Be: Handwritten logbooks Computer printouts Strip or circular recording charts from continuous emission monitors 39

40 Compliance Testing Initial source testing Larger units require two consecutive annual source tests for dioxins Other Permit Conditions Operations and Maintenance Manuals Operators must be familiar with manufacturer s Operation and Maintenance Manual. Be operated per manufacturer s instructions, unless conflicts with district rules. Operator Training Requirements Dioxin: Chemical Structure 40

41 Requirements for all Medical Incinerators Be operated such that ash and scrubber residue are handled and stored in a manner that prevents entrainment into the air. Operated only by individuals who have a certificate of training issued by the American Society of Mechanical Engineers, or other training approved by the APCO. Additional Requirements: Burning 10 to 25 tons per year Initial source test using ARB Test Method 428. Dioxins < 10 nanograms per kg of waste burned. Provide information on waste composition (moisture content, amount of infectious, pathological, hazardous). Test at within 10% of maximum firing capacity. Additional Requirements: Burning more than 25 tons per year Dioxins emissions reduced by at least 99%, or less than 10 nanograms per kg of waste burned. Flue gas at outlet of AP control equipment not to exceed 300 F. Primary chamber above 1400 F, Secondary chamber above 1800 F, one second residence time. Continuous Data Recording System Maintenance and Calibration records maintained. Two annual source tests until two consecutive tests demonstrate compliance. 41