Created to improve wash quality. Now, they play a major role in environmental compliance.
"Dual-phase" traces its roots to a concept Washex introduced in the '70s when that company unveiled a machine that drycleaned and then water-washed. Drycleaning would remove many soils and stains, but not all of them. It couldn't handle excessive perspiration or food, but it did a nice job with oil and grease. Also, the second phase assured there was no chance of lingering drycleaning odor, because you'd waterwash out the solvent.
A new twist on the dual-phase concept is helping industrial launderers deal with environment-related concerns. One U.S. company is using dual-phase with a third process - steam stripping of volatile organic compounds (VOCs) - in the same machine. Another operation has just steam stripping and waterwashing (plus extraction) in one machine.
Environmental concerns sparked the creation of both of these machines from Ellis Corp. (Itasca, IL). Jeff Davis, Ellis' technical director, believes such machines will be the key to clean air compliance in the future. Laundries concerned about keeping VOCs out of the sewer are probably already treating their wastewater. But those facilities that need to avoid permitting under Title V of the Clean Air Act are just beginning to realize how to minimize their potential to emit VOCs into the air from their washroom and dryer stacks.
Even if you have a wastewater treatment system, stripping keeps the VOCs out of your water, which means you can keep them out of your sludge. That saves landfill costs.
It might seem that the market for these machines would be limited to shop-towel specialists - especially when you consider the size of the the two units now in operation: 900-pounders. But you can still make economical use of the technology with an average amount of towel business, Davis notes. The units can be used as conventional washer—extractors for all kinds of work. And if you don't have the volume of work needed to keep such a large machine running full all the time, there's little economic harm in washing under capacity.
That's probably what you do anyway because of safety concerns. "If you've got any solvent-laden towels, you don't want them sitting around for a long time," he notes. "Nothing prevents you from washing 400 pounds in a 900-pound machine. It's less efficient in terms of chemical use. But the cycle time and labor would be almost the same per pound."
Most likely, though, dual-phase will appeal to high-volume users who specialize in heavy-soil work. One of the companies now employing this technology is a solvent washer that subcontracts for other laundries; the other is a waterwasher known for its environmental compliance record.
In the first case, drycleaning comes first, then VOC stripping, and finally, waterwashing. The latter helps to pull the drycleaning fluid out of the work following extraction, the used solvent and water wind up in a separator outside the machine. In both cases, the stripped VOCs wind up in that same separator and are recaptured.
In the VOC stripper/washer-extractor, the process starts with the pressurized steam flashing off the solvents, which are collected in a condenser. From there, they flow into the separator and are stored for reuse, while the water settles to the bottom and the solvents float. A normal wash cycle follows.
Davis expects limited demand for the drycleaning/waterwashing machines from industrial launderers: "People who have gotten out of drycleaning probably won't get back into drycleaning." A more significant market exists for the stripper/washer combination because of Title V regulation, he says.
If you do two 800-pound loads a day of shop towels, you may have enough emissions to cross the permitting threshold for volatiles: 100 tons a year in many locations, and less in areas with greater air pollution problems.
Programming and operating the machines are equivalent to these tasks for conventional washer-extractors. "All controls are computerized; you don't have to do any more than just a normal washing," Davis observes. "The cycle time is longer because you're adding a process, but it's not necessary to run to the machine halfway through a cycle and adjust it, or to put in any more chemicals."
Dual phase solvent stripper/washer-extractor uses external separator to keep VOCs out of wastewater.Controls are explosion - or flamability proof (i.e., they're sealed so that if there's a stray spark, they won't create an explosion). The drycleaner that has this type of machine (the company has four of them in one plant) has a control room; the waterwasher has controls on the machine (it has just one such machine in its plant). Other features include the standard options available on Ellis machines.
Any company that invests in such machinery is in a good position to expand its wiper business. Many laundries are content with profit from rental of other products and will handle shop towels only to get other business. They subcontract the work elsewhere. With VOC stripping, they can keep this business and reap the profits.
This doesn't mean that customers can leave more solvent in their towels, though. "You don't want anything dripping in your trucks. If one of your trucks gets pulled over, and a load of shop towels is leaking, the whip comes down," Davis says. Launderers must continue to insist on no free liquid.
How heavy is regulatory pressure? Davis theorizes that local authorities are waiting for the coming federal standards that will govern the industry, and are holding off on further regulation until it's clear what discharges they will cover.
"For the most part, local POTWs aren't going to push laundries until the standards come out, especially if they're not being pressed too hard by EPA to comply with their own discharge permits," he says. Thus, it's likely that the "neutral zone" in which laundries now find themselves will disappear when the regulations go into effect in 1999.
And if VOC content in wastewater is an issue under these new federal standards, the stripper/washer-extractor will be ready and waiting for those who will have to contend with this problem.
- Industrial Launderer