Reduce VOC Emissions and Costs

Pollution abatement systems are designed with heat recovery systems that can reduce overall energy costs.

VOCS IS A four-letter "word." So is cost. Package printers working with solvent-based inks must deal with these profanities on a continual basis—eliminating the emission of VOCs (volatile organic compounds) and other air pollutants, while minimizing costs. It's a dual-edge sword that has gotten sharper over the past couple of years due to significantly higher energy costs.

VOCs, along with nitrous oxide (NOx), are detrimental to air quality because of the ozone that is produced when sunlight acts on these pollutants. Ozone is the primary component of smog, and since it is not emitted into the air by any specific sources, it must be controlled by eliminating the ingredients that produce it. This explains one of the reasons for the focus on VOCs and other hazardous air pollutants (HAPs).

Air pollution solution

Those companies in the business of providing solutions for eliminating VOCs in process air streams have long offered options and design features for reducing energy-related costs. However, during times of increasing energy bills, cost reduction opportunities get a renewed focus, and some companies can take advantage of the situation by being able to justify upgrades and/or new equipment installation that provide a good business return.

Jim Alamena of Glenro Inc. (Paterson, N.J.) says that companies like Glenro that also supply industrial dryers can take further advantage of cost reduction/energy recovery opportunities. Depending on a customer's needs, Glenro can supply pollution abatement equipment such as regenerative thermal oxidizers, recuperative thermal oxidizers, and catalytic oxidizers integrated with process dryers and heat recovery systems in complete, turnkey processing packages.

To augment its pollution abatement line, Glenro introduced a new line of regenerative thermal oxidizers (RTOs) earlier this year. Called Regenex™, this system combines high heat recovery and a compact package to achieve guaranteed VOC destruction efficiencies of 99 percent-plus. It can be used for low VOC concentration applications when catalyst systems cannot be used due to cost concerns, or when catalyst-destroying chemicals are in the solvent mixture. It can also be used when flexibility is needed to handle many products with different solvent mixtures running on the same line. Depending on the application, up to 95 percent of the combustion heat can be recovered and recycled.

The CMM Group (DePere, Wis.) also supplies both air pollution control systems and industrial web dryers. It provides custom-designed equipment with guaranteed VOC and/or HAP destruction efficiencies of up to 99 percent-plus. Sizes are available to treat exhaust process air streams from 3,000 scfm to 100,000-plus scfm. Again, depending on application parameters, primary heat recovery efficiencies of 80 to 95 percent can be achieved to significantly reduce energy costs.

Maverick Enterprises, Inc. (Ukiah, Calif.), a printer of custom-designed aluminum and polyethylene foils used to cover the tops of wine, liquor, and food bottles, is in the process of installing a CMM Group, custom-designed system to control exhaust emissions from dryers on its rotogravure printing presses. This air pollution control system uses a 15,000 scfm Regenerative Thermal Oxidizer to capture and destroy the VOCs. It is designed to exceed local, state, and federal clean air regulations, destroying greater than 95 percent of the VOC emissions from the company's printing operations.

Brian Cannon, sales director for Adwest Technologies (Anaheim, Calif.), notes that many state and local agencies are stressing longer term abatement-system uptime and compliance, along with energy efficiency. Adwest designs a true 95 percent thermal efficient heat exchanger into every RETOX® RTO at the full flowrate (available up to 80,000 cfm). Cannon also says the RETOX RTO oxidizers are designed for simplicity and reliability, along with a flameless RTO operation that provides users with 99 percent-plus VOC destruction with virtually no NOx generated as a byproduct of combustion.

Gravure printer reaps benefits

One of Adwest's customers has been realizing the benefits of the energy efficiency and reliability built into the RETOX systems for several years now.

This midwest printer and web converter installed a 35,000 scfm RETOX Dual Chamber RTO to replace an aging and inefficient recuperative thermal oxidizer system at its central Wisconsin gravure printing and packaging facility. According to Project Manager David Swinehart of Controlled Environment Equipment (North Prairie, Wis.), the primary turnkey construction contractor for the environmental upgrades and expansion project, "The Adwest Technologies RETOX RTO system was initially projected to save over $400,000 in natural gas and electric costs in the first full year of operation. The actual savings was just over $470,000 and has grown every year due to increases in utility costs. Our client's facility is achieving greater than 99 percent VOC control with the RETOX RTO, while the flameless operation does not generate any nitrogen oxide byproduct."

Adwest Technologies designed this system to provide 95 percent primary heat recovery at the 35,000 scfm maximum flow rate from the rotogravure printing presses. When necessary, the printer has been able to run up to 42,000 scfm through the RETOX RTO and still obtain 99 percent VOC destruction. This provides needed flexibility for the printer when an older afterburner system sometimes does not operate well.

The RETOX RTO also has an integral heat exchanger bypass system that allows for operation from 0 to 25 percent LEL (lower explosive limit) solvent loadings. This is helpful since the printer does a wide range of custom short- and long-run gravure printing at various color coverages.

Each RETOX includes PLC-based controls with online remote telemetry diagnostics that allows 24/7 technical service support if needed. Swinehart claims that the RTOs have required very little maintenance, just an occasional thermocouple change, lubrication of the main fan motors, and assurrance that the compressed air supply is dry in the winter.

While many end users focus solely on initial capital cost, Swinehart urges prospective users to evaluate the energy costs over the 10-20 year life span of the VOC control system, in addition to any maintenance and major component replacement (catalyst, carbon, ceramic media, etc.) that may be needed. His final recommendation: "Once your RTO is installed, you will have to live with the energy usage for many years, maybe decades, so make sure that you have the lowest gas, fan horsepower, and electric costs in your RTO system upfront and that your supplier has extensive installation experience in similar applications."

by: Tom Polischuk