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AFTERBURNERS / THERMAL OXIDIZERS

Nutec Bickley design and manufacture a range of Thermal Oxidizers, which are also called Afterburners.

They are used to remove Volatile Organic Compounds (VOCs) from a kiln exhaust stream to ensure emissions meet environmental regulations. As they destroy the VOC there is no further treatment required.

The design is specific to the compounds released but Time, Temperature and Turbulence must be present to ensure that oxidation is complete.

Correct control of these 3 Ts as well as excess air levels (≥ 3% O) can ensure that VOC levels can be reduced by 99.99%.

The afterburner temperatures should operate at temperatures above the compounds Auto Ignition Temperature for a time depending on the % of VOC destruction required.

See table below showing VOC Destruction efficiency Versus time and temperature. The time the gases remain at the temperature (Residence Time) is related to the flow and the amount of turbulence.

Destruction Efficiency (%)
Degrees above Auto Ignition temp (ºF)
Degrees above Auto Ignition temp (ºC)
Residence Time (Secs)
95 300 150 0.5
98 400 200 0.5
99 475 250 0.75
99.9 550 300 1.0
99.99 650 350 2.0

 

Different Compounds have different Auto Ignition Temperatures (AIT) but a list of common VOC’s is given below

Compound
Auto Ignition temp (ºF)
Auto Ignition temp (ºC)
Acetone 869
465
Ammonia
1,204
651
Benzene
1,097
591
Butanol
693
367
Carbon Disulfide  257
125
 Carbon Monoxide  1,128
 608
 Chlorobenzene  1,245
 673
 Ethane  950
510 
 Ethanol  799
426 
 Ethylene Glycol  775
 413
 Hydrogen  1,076
 580
 Hydrogen Cyanide  1,000
538 
 Hydrogen Sulfide   500
260 
 Kerosene  490
 254
 Methane  999
537 
 Methanol  878
470 
 Petroleum Naphtha  475
 246
 Nitrobenzene  924
 495
 Propane  874
467
 Propylene  940
 504
 Styrene  915
 490
 Trichloroethane  932
 500
 Toluene  997
 536
 Turpentine  488
253 
 Vinyl Acetate  800
 426
 Xylene  924
  495

 

Shuttle Kiln Afterburners

When an Afterburner is used on a shuttle kiln in needs to be designed and sized carefully to be sure to remove the organic volatiles during the specific times that they are released from the product.

The Afterburner normally operates at 700º -1000°C and it is important that the retention time in the afterburner is enough to remove the organics to the required level.

The process often starts slowly as soon as the kiln temperature starts to increase; it reaches a peak between 300°C and 500°C and then reduces until all the organics are removed by 700º - 800°C. In a shuttle kiln it is now possible to turn off the afterburner to save fuel.

As the energy needed heat the exhaust to the required temperature is high, Nutec Bickley often include a heat exchanger to pre heat the exhaust flow and also to capture as much waste heat as possible for pre heated combustion air for both the kiln and the afterburner. This heat recuperation improves the overall efficiency of the system.

Tunnel Kiln Afterburners

When an afterburner is used on a tunnel kiln the product in the kiln reaches the off-gas temperatures more gradually instead of all at once, but the total product volumes are usually larger.

The system can be designed to exhaust at higher temperatures but often this is less effective than to use a heat exchanger to preheat the exhaust gases as they leave the kiln but before they reach the afterburner as the hot side of the heat exchanger is fed from the afterburner exhaust.

Special burners with reduced external air supplies can be used in tunnel kiln afterburners as there is usually enough Oxygen in the exhaust gases to complete the combustion. The focus with all afterburners is to reduce fuel usage whilst maintaining acceptable emission levels.

tunnel-kiln-afterburners

Advantages of Nutec Bickley Afterburners

  • Designed with the kiln to ensure maximum efficiency and Destruction Efficiency
  • Vertical or Horizontal afterburners are available to fit all areas
  • Used in conjunction with Heat Exchangers to increase efficiency and reduce energy costs

 

 

  • 50 years’ experience supplying afterburners to many applications
  • Control systems to ensure afterburner only operates when it is required
  • Supplied with test points to ensure Environmental Compliance

Industries we serve

  • Refractories
  • Continuous Casting Refractories
  • Basic Refractories
  • Monolithic Refractories
  • Abrasives
  • Ceramic Cores
  • Technical Ceramics

Processes where Afterburners are used:

  • Firing with Binders/ Organics
  • Sintering
  • Tempering
  • Curing
  • Burn Out
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Industrial kiln benefiting from the best technology

SCADA

With our SCADA systems, kiln operators are able to have complete control of their firing process, enhancing efficiency and productivity. Our latest Industry 4.0 developments integrate the latest technology to not only monitor the process, but also to keep the kiln operating at peak performance with smart maintenance technology. All the data generated during the firing process is stored in our SCADA system, which is then used to generate reports, graphs and intelligence data, to help customers in their decision making process.

 

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Why Nutec Bickley?

  • Nutec Bickley is one of the world’s leading manufacturers of heat treatment furnaces and a technology leader.
  • With our fully equipped research and development facility we are able to provide innovative solutions tailored to our customers’ specific product requirements.
  • Pre-assembly of furnaces at our fabrication facility provides a guarantee of quick and easy field installation, while test firing verifies that all components are in proper working condition, thereby minimizing commissioning issues on site.

 

  • We supply furnaces to customers involved with steel, titanium and aluminum production as well as forging, automotive, aerospace, commercial heat treating, electronics, wind energy, medical equipment and nuclear industries. Visit our website below for more information.
  • Customers are welcome and indeed encouraged to come and see our testing procedures to make sure they are receiving the end product just as they expected.
  • We provide automation & material handling solutions.

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