Air Pollution Advice

Auto Shredder Installs RTO & AGS for VOC Emission Control

Written by Jan Carlson | May 21, 2021 4:29:41 PM

Catalytic Products International (CPI) installed a Regenerative Thermal Oxidizer (RTO) at a Midwest metal recycling facility for the control of Volatile Organic Compounds (VOCs) and odor emissions.

  • Process Type: Auto and Metal Shredding
  • VOC: Various Hydrocarbons & CFCs
  • Process Air Volume: 80,000 scfm
  • Control Type: Regenerative Thermal Oxidizer (RTO) and Acid Gas Scrubber (AGS)
  • Destruction Rate of Efficiency (DRE): RTO: 98%, AGS: 99%
  • Tested DRE:  99.0% with Method 25A
  • Installation: CPI installed RTO & AGS

The pulverizing and shredding of scrap material leads to the liberation of particulate emissions as well as volatile organic compounds (VOCs), hazardous air pollutants (HAPs) and nuisance odors.  In addition, ELVs and appliances which are not completely drained of refrigerant fluids can emit chlorofluorocarbons (CFCs) leading to acid gas emissions.

Air pollution control in metal shredder facilities has historically been focused on the containment of metal shredder residue (MSR) utilizing cyclones, baghouses, scrubbers, and suppression technologies. While these technologies are effective for containing particulate matter (PM), they are not sufficient to control the harmful VOCs which can pass directly through these systems and into the atmosphere. Specifically, end-of-life vehicles (ELVs) and appliances which are not completely drained of gasoline or refrigerant fluids can emit chlorofluorocarbons (CFCs).  

The metal shredder emissions control system consisted of three (3) main components:

Particulate Control

An existing indexing filtration system removed liquid and solid fine particulate emissions prior to the inlet of the RTO.

Regenerative Thermal Oxidizer (RTO)
The 80,000 SCFM Regenerative Thermal Oxidizer (RTO) will control VOC emissions from the metal shredder process exhaust with 98% destruction rate efficiency (DRE) and a thermal efficiency of 95% allowing the facility to meet compliance goals and reduce operational costs. 

In this application the process exhaust VOCs contain the elements fluorine and chlorine. These will ultimately oxidize to form gaseous hydrogen fluoride (HF) and gaseous hydrogen chloride (HCl). Condensing moisture can also absorb the HF and HCl to form strong acids. Based on the potential for strong acids and to provide additional corrosion resistance, all “wetted” surfaces which interact with the oxidizer’s flue gas were constructed of Duplex stainless steel.                               

Acid Gas Scrubber (AGS)

At the exit of the RTO, a packed tower acid gas scrubber captures and controls the emission of the acids formed during the combustion process. The scrubber operates at 99% removal efficiency.             

 

                                                                             

CPI worked closely with the Engineering, Procurement, and Construction (EPC) firm as well as the end user customer to define, select, and engineer the equipment best suited to safely and effectively treat emissions from the metal shredder process exhaust.  https://www.recyclingtoday.com/article/general-iron-auto-shredder-voc-emissions-control/ 

CPI provided a complete turn-key installation, including engineering, design and supply of the RTO and scrubber. The installation of the RTO and related equipment included concrete pad design, ductwork design and sizing, booster fan, and media loading into the RTO and scrubber. CPI provided on-site supervision to ensure coordination with the EPC and their subcontractors as well as the final customer. This approach guaranteed that entire system was installed correctly, returning the customer to fully operational status with minimal downtime.

UPDATE: Stack Test Performed

VOM destruction efficiency testing was performed pursuant to USEPA Method 25a.  The VOM emissions at the RTO inlet and scrubber outlet were adjusted to subtract methane and ethane pursuant to Method 25a.  The demonstrated average VOM destruction efficiency was 99.0%.

 

CPI has been “Enabling Clean Production Since 1969” and continues as a leading supplier of air pollution control equipment. CPI is at the forefront in providing industries including the metal recycling industry with solutions to their air pollution control needs.

Today, CPI partners with its customers as a trusted resource in resolving the most complex air pollution and energy conservation problems. We provide our customers with innovative and cost-conscious solutions to their most complex VOC, NOx, and Odor pollution challenges. Our equipment is also at work meeting energy conservation strategies and minimizing greenhouse gas (GHG) emissions.