Efficient, Flexible Tunnel Washers
CHICAGO — Tunnel washers have been a staple for high-volume laundries for decades, but over the past 10 years, the multiple-module washers have seen some giant leaps forward in technology and efficiency.
“Tunnels today have much more flexibility in terms of design, water flows, controls and the ability to wash multiple products in the same run sequence,” says Keith Ware, vice president of sales for Lavatec Laundry Technology Inc., with U.S. headquarters in Beacon Falls, Conn.
“When we think back just five to seven years ago, some of the batch washer technology was still pretty mundane,” says David Netusil, manager-sales support and marketing for JENSEN USA Inc. in Panama City, Fla. “Sure, we were at the point where we were washing goods well below 1 gallon per pound, but we really hadn’t eclipsed the .5 gallon per pound threshold with truly excellent wash results.”
Steve Wilbur, director of engineering and product development for G. A. Braun Inc. in Syracuse, N.Y., adds that tunnel washers have achieved water usage rates as low as 0.3-0.4 gallons per pound. He feels that tunnels have likely gone as low as they will be able to in terms of water usage.
“One area that has benefitted over the past decade is the reuse of other plant heat sources to preheat incoming water and to reuse heated water within the tunnel process,” he says. “This has allowed tunnels to become very energy efficient surpassing most all other conventional equipment.”
Netusil says his company also sees the most notable and advantageous technological improvements in tunnel washers to be in water usage methods and water disinfection/sanitation.
“In terms of water usage methods, JENSEN utilizes our patented QuickSoak technology, which is a very straightforward extra shower for the linen in the first compartment for maximum soaking, and saturation of chemistry,” he shares.
Netusil says disinfection of reuse press water has been achieved through the use of UV technology.
“This technology has advanced rapidly over the past two years or so and is producing some pretty extraordinary results,” he says. “This increases the amount of press water that can be reused due to a complete disinfection and oxidation of the press water, thereby decreasing water consumption and allows for a clean and sanitary press water tank.”
Darrell Redler, marketing director for systems for Pellerin Milnor Corp. in Kenner, La., says that in the last 10 years, the company has improved on its tunnel washer in two ways.
“First, we introduced the PulseFlow® batch washer in 2009,” he says. “This design changed the way we use counter-flow, an important feature of all Milnor batch washers, by postponing the counter-flow until it is most needed. Then in the last year or so we made the dual PulseFlow tank standard for all tunnels going forward. This allowed for better control over, and use of, the fresh water required in the washer.”
Tony Jackson, director of national accounts for Kannegiesser ETECH in Grand Prairie, Texas, shares that the Kannegiesser PowerTrans VARIO is a modern batch washer that combines flexibility, performance and the lowest total consumptions. Separate batch washing ensures precise process control of each single batch without any liquor mixing between neighboring batches.
He further shares that the versatility of a complete standing bath washing-and-rinsing system allows for color changes without the need for empty pockets. With the large drum volume and straight wall design, the PowerTrans tunnel creates a hygienically clean wash environment while keeping each batch separate.
Ware says Lavatec has developed systems to capture flushes from loads with different colors into reuse tanks, rather than losing that water down the drain. The next time a load with similar colors is injected into the tunnel, this water is brought back into the wash/wet out compartments and effectively reusing the water.
Although some design enhancements have been made allowing for better lift and drop in a tunnel’s mechanical action, the primary factor that has changed is the ability to program the angular degree of rotation of the tunnel enhancing the effect of the rib design, says Wilbur.
“This allows for programming different wash angles for different types of goods and soil factors,” he points out. “The key to taking advantage of this is like goods and like soil factors must be run together as the programmed wash angle will impact all goods in the tunnel.”
Ware says varying mechanical baffles can alter the mechanical action to be as aggressive or gentle as necessary. Frequency inverters have also improved the flexibility on controlling the mechanical action by programming the speed and the rotation angle of the inner drum. It can be programmed separately in each wash program and specific to the individual item being processed.
Improved steam valves and double drum insulation also help to maintain heat inside of the tunnel for improved energy efficiency, Ware points out.
“Often our customers look to use cold or tempered water in the tunnel,” he shares. “This creates the need to heat tunnel water with steam injection, which is the most inefficient way to heat water. It takes nine times more energy to turn hot water into steam, compared to heating water through conventional methods.”
Finally, Ware says presses have become faster and with higher pressures to remove more moisture from the product to improve dryer efficiency.
Joseph Amaral, vice president of corporate sales for RAMCO Laundry Machinery Inc. in Arlington, Texas, says changes and upgrades to its press include going from 27 to 45 psi/bar pressing ability with 99 available programs.
“This allows us to extract more water from specific items and create programs to avoid damaging fragile items,” he says. “This creates less water, faster dryer times, less energy cost, fast turn time and great productivity.”
Controls have been one of the biggest advances in tunnel washers, in Ware’s opinion, with more precise data, drum rotation and speed, and having the ability to monitor water through induction meters to provide more precise water injections. This results in more precise temperature controls, chemical formulation and data collection.
Tunnel controls have evolved and migrated to almost exclusively touchscreen controls, Wilbur says. These controls have begun to incorporate artificial intelligence (AI) features.
“These AI features allow the tunnel to predict component problems before they happen, alerting both plant personnel and the tunnel equipment supplier,” he points out. “They can tell mechanics when to do preventive maintenance steps, and actually show maintenance folks how to do them through the use of videos.”
“Since the late 1990s Milnor has used industrial PC-based controls to run the CBW washer’s main operational application, or Mentor,” says Redler. “Like all computer applications, over time they undergo many changes and improvements.”
In the case of Mentor, he says these improvements include the ability to handle more customers and formulas, a more intuitive user interface, improved graphical displays, touchscreen controls, and the ability to communicate with non-Milnor systems using data fusion techniques.
Amaral agrees that one of the biggest improvements in tunnel washers over the years has been in software and touchscreen capability.
“We have been able to use upgraded software improvements to pinpoint mechanical problems before and during failure or issues,” he says. “We can troubleshoot products and assist remotely. And schedule and send e-mails on preventive maintenance.”
Chemical and water usage can be programmed to a more accurate and precise measure to ensure high quality of product, while reducing cost and waste, says Amaral. The ability to have more programs to specialize helps ensure the proper processing and overall care and cleanliness of the product.
“The management side has so many more functions and features, which include customer identifications, product selection, accounting and billing features,” he adds. “Not to mention the upgrades in material handling. You can move product, change production schedule system of goods being processed with the touch of your fingertips.”
Wilbur says the big change in tunnel washer chemistry over the past decade is a move to use peracetic acid-based chemistry, which in turn allows for processing goods in lower temperatures, thus saving energy throughout the tunnel processing.
Redler says that one of the issues with continuous counter-flow was that it made for continuous dilution of soil which was good, but with that came a dilution of the chemistry which meant higher dosing to compensate.
“PulseFlow washers allowed the chemistry to work during the standing bath phase of the transfer cycle, resulting in chemical savings without any loss of quality,” he says.
Braun’s batch washers utilize Braun’s Tunnel Infusion Technology® throughout the tunnel, Wilbur says.
“This trademarked fill process technology consists of adding water and chemistry above the goods providing superior agitation and mixing,” he says.
One area of the tunnel washer that hasn’t changed all that much is its footprint. However, Wilbur says that the benefits afforded by developments in the chemical field, and those already noted regarding mechanical action, have allowed shorter tunnels (fewer chambers) to increase their effective output.
“This along with the improved efficiencies of today’s dryers can free up some valuable facility space,” he says.
Jackson shares that the VARIO is built to reduce waste with intelligent water management, maximized loading volumes, and efficient rinsing times. Customers are also able to produce the highest possible output within the available space due to the efficiently designed footprint of the systems.
Tunnels are used in almost every industry from healthcare, to hospitality, to food and beverage and everything in between. There are many factors that a prospective tunnel purchaser needs to consider, but probably one of the key factors is mix, and current and projected volume. Tunnels fall off on efficiency when used in low volume situations, so that is probably the key factor to consider first, Wilbur points out.
Ware agrees that determining what size tunnel is best for any operation is the key to success for operational efficiency.
“Utilizing a large-capacity tunnel for smaller COG accounts does not make sense, since most of the compartments will be under loaded,” he says.
However, Wilbur does say that with the increase in efficiency, the return on investment (ROI) for the purchase of a tunnel system has become more attractive to the smaller users.
“We are seeing a lot of smaller laundries automating the wash process,” observes Seth Willer, national sales manager for Girbau Industrial in Oshkosh, Wis. “Rising labor rates are pushing owners to improve labor efficiencies with machines. Even though the upfront cost to purchase a tunnel is a big sum, especially for smaller operators, in the long run, the return on investment is typically no more than three years, at most. It’s time to consider upgrading to a tunnel system if your laundry processes 1,500 to 2,000 pounds of laundry per hour.”
Ware says laundries also need to determine what they want to process, how diverse the product mix is, and if they have the space, budget and return on investment for developing a tunnel project. The driving factors are labor, utilities, throughput and efficiency.
“For example, we worked with a company that primarily had washer-extractors,” Ware shares. “The reason to move to a tunnel was their inability to find people to work in the washdeck area and reduce the significant number of workers’ compensation injuries in their plant. Working together, we found a solution to help with this issue. We also improved their operating costs and reduced utilities.”
Redler says the main factors that dictate the use of tunnel washing are minimum output requirements and whether or not the plant is capable of supporting the equipment.
“Beyond the purely physical aspects of sizing and output, the costs involved for the equipment are usually near the center of attention,” he adds. “However, considering the cost savings due to the inherent rationing of water and utilities, and the labor-saving benefits possible through automation, a reasonable payback is typically realized.”
Willer adds that operators looking at a tunnel need to look beyond the washer itself in terms of laundry operation.
“Don’t forget what you wash, you also must dry, iron, fold and put away,” Willer says. “The amount of laundry a tunnel produces per hour can be overwhelming without properly sized ironing systems, towel folders and space for carts, soiled goods and clean goods. Tunnel systems also need ample ceiling height, because dryers unload by gravity, and require specific utilities. Consider all of this when looking into a tunnel purchase.”
Tunnels will continue to improve quality, flexibility and energy conservation in the future, Ware says.
“I believe that tunnels will develop more intuitive controls for chemistry of varying load weights,” he says. “Considering that the number of highly skilled maintenance engineers is not keeping pace with industry growth, future considerations should focus on simplifying the tunnel system. Predictive maintenance will become more important as laundries utilize their resources more effectively and over longer operating hours.”
The biggest improvement of a tunnel washer’s throughput in the future will be improving speed of the extraction presses and removing moisture faster, with less damage to the linens being pressed, Ware says.
“Tunnel technology will continue to improve, becoming more affordable, reliable, efficient, simple to use and easy to maintain,” adds Willer. “The other neat thing is that tunnels are very flexible, so they easily adapt to new technologies in water heating, UV disinfection, chemicals, conveyors and overhead sling and sorting systems. As these ancillary systems improve, the entire washing process also becomes more efficient.”
“Undoubtedly, design engineers are always working on the ‘next big thing,’” says Netusil. “What will they come up with? Time will only tell.”