Case Study: Styrene Emissions: Catalytic Oxidizer With Concentrator

Industry

Composites / Fiberglass

Problem

The world's largest button manufacturer needed a pollution control system that would destroy styrene emissions from a variety of plant processes. The plant was proactively seeking a cost-effective air pollution control solution to preempt future regulatory action. The main concern of the customer was the high operating cost of an emission control system.

Action

After thorough evaluation of several possible technology solutions, the company selected Anguil Environmental Systems, Inc. (Anguil) to process their styrene emissions. Anguil recommended a unique solution, a Rotor Concentrator coupled with a Catalytic Oxidizer, to destroy the VOC concentration. A key factor was Anguil's ability to lower the volume of air that needed to be treated by achieving a 10 to 1 flow rate reduction with the Rotor Concentrator. Anguil provided the customer with a static pilot test to prove the effectiveness of the concentrator wheel on styrene. The successful results from the static test ensured the customer's confidence in the new application of the concentrator technology to control styrene emissions.

Solution

Three main considerations guided the design of this solution: the need for an emission control system with low operating costs; the control of the high volume, low volatile organic compound (VOC) concentration of the process air stream; and the unique characteristics of styrene.

Many of the processes that emit styrene - such as boat building and FRP - have high airflows with low VOC and styrene concentrations. Button manufacturing presents a similar problem but on a slightly smaller scale; the plant's airflows were approximately 15,000 SCFM with styrene concentrations ranging from 50-200 ppmv. The customer considered a regenerative thermal oxidizer (RTO) and a biofiltration system as other possible solutions. While effective in destroying styrene, both of these would have been very expensive solutions because higher air flows result in higher costs for treatment technologies. The operating costs of the RTO and the biofilter were much higher than Anguil's solution because these systems had to treat the entire 15,000 SCFM of process air.

Anguil's solution, a rotor concentrator coupled with a catalytic oxidizer, reduced the process air that needed to be treated by a factor of 10. The high volume airstream, approximately 15,000 SCFM with 50 - 200 ppmv of VOC, is passed through the rotor concentrator wheel where the VOCs and styrene are adsorbed in the bed, purifying the high volume air. This high volume air is then exhausted to atmosphere. The concentrator wheel rotates continuously, transporting adsorbed VOCs into a desorption section where they are desorbed from the adsorptive media with a low volume heated airstream. After being desorbed from the wheel, the air volume has been reduced from 15,000 SCFM to about 1500 SCFM and the VOC concentration of the air stream is increased to about 500- 2000 ppmv. This low volume, high VOC-laden air is then processed by the oxidizer. By isolating and treating the lower air volume, Anguil is able to provide a system with far lower operating costs than other emission control systems.

Anguil was able to further reduce the operating cost of the system by utilizing a catalytic oxidizer to destroy the concentrated, contaminated air stream. Anguil's experience with styrene emissions has demonstrated the easily-oxidizable nature of styrene in the presence of catalyst. Catalytic oxidation systems typically achieve greater than 99% destruction of styrene with relatively low temperature requirements. An Anguil Catalytic Recuperative Oxidizer designed for 1,500 SCFM was installed to process the VOC-laden airstream with minimal auxiliary fuel consumption.

The final design consideration was to address the unique characteristics of the styrene emissions. Because the rotor concentrator wheel is a relatively new technology, there are only a few examples of concentrator wheel technology in the styrene industry. The customer was concerned with the possibility of styrene polymerization on the wheel and subsequent system failure. Anguil had performed extensive tests to establish that certain zeolite formulations function better than others in the presence of styrene and eliminate the possibility of polymerization. However, Anguil went the next step in order to relieve the customer's concerns. Working closely with one of their technology partners, the Engelhard Corporation, Anguil ran several static (live) pilot tests to prove the effectiveness and reliability of the concentrator/oxidizer technology. This testing process convinced the customer to move ahead with the Anguil solution.

Another benefit to the customer of the rotor concentrator/oxidizer system was low maintenance cost. The zeolite material has an expected life of 10 years under continuous operation. The easy regeneration and durability of zeolite provides considerable savings over the constant maintenance and replacement required of carbon beds. Additional maintenance savings come from the durable design of the rotor concentrator. The concentrator wheel is rotated with a simple motor and belt drive -- reliable components that last at least five years and require minimal maintenance.

In order to expedite installation, Anguil assembled the entire system in its manufacturing facility, allowing for customer review and inspection prior to shipment. The system was then re-erected in the field and integrated into the customer's process. Anguil's combination of proven experience and technologically advanced air pollution control products have led to another satisfied Anguil customer.