User Solutions
(Issue 15, 2009)
Denim Manufacturer Upgrades Controls to
Add Flexibility to Process Lines
By Jonathon Payton
Mount Vernon Mills
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Nestled along the Chatooga River, in Trion, Georgia, Mount Vernon Mills is one of the largest and oldest textile mills in the United States. Its long history dates back to 1845. The initial 5,000 square foot two-story mill had 40 employees and produced 5-lb. bunches of yarn to sell to local merchants from wagons.
Over the next 160 plus years, the mill survived General Sherman’s march through Atlanta, a fire in 1875, bankruptcy in 1912, two World Wars, the fight to become unionized, and a major flood in 1990. Through all of this, the mill has continually expanded, renovated, and modified in order to tailor its end products to change with the times. The mill has produced many different products over the years, including fabric used for military uniforms, crop sacks, sheeting, shirting and even gloves.
In 1971, the decision was made for this Trion, Georgia, plant to produce denim. This turned out to be one of the best decisions in the mill’s history. By installing new equipment, the plant rode the wave of growth in the denim industry. By 1976, Mount Vernon Mills had over 1,100 looms producing denim. The company continued to grow, but nearly experienced disaster when the “Hundred Year Flood” hit Trion in 1990. The company spent the next several years modernizing its plant with state-of-the-art machines to gear up denim production.
After its latest round of renovations, the mill now operates with state-of-the-art machines in over one million square feet of manufacturing space. Denim from Mount Vernon Mills is woven and finished for sale to many major manufacturers across the country, such as Wrangler™ and Lee ™. Mount Vernon is now the third largest producer of denim in the United States. (See Figures 1 & 2)
Figures 1 & 2, Denim Finishing line at Mount Vernon Mills
Over the years, the company has endeavored to continually upgrade machines and technologies, and the past few years have been no exception. On some of the finishing ranges and re-beamers, control systems still worked, but finding replacement parts had become more difficult, thus making it harder to give operators features and functions they wanted. Even modest changes and modifications were difficult based on the age of the control system. Late in 2006, the mill decided to embark on upgrades for re-beamers and one of its finishing lines.
The task of replacing the control system for the finishing line, a very large multi-motor machine, seemed daunting. All the motors have to work together and are self-adjusting, with dancer position sensors which send signals back to a PLC system. The PLC system automatically adjusts motor speeds to keep everything running together.
Because of the machines’ size and complexity, the mill sought bids for the work. When job bids came back with costs far exceeding budget, the decision was made to use AutomationDirect components, and do the whole project in-house. To save time, new backplanes were purchased to bolt onto the old cabinet back so they could be assembled and tested before installing in the machine. This task would be performed in the system designers’ spare time over a period of three months. They ended up having only three weeks to build and no time for testing. Electricians were finished mounting the motors and drives before programmers had the software completed.
The old finishing line was powered by DC drives with field regulators. The new system has been upgraded to AutomationDirect’s Durapulse AC Drives all networked via Ethernet to a DL-260 DirectLOGIC PLC System. A 15” C-more touchscreen operator panel was chosen to replace the main operator console. The mill purchased, installed and programmed the entire system within the three weeks allotted. All HMI and PLC programming was performed in-house, and AutomationDirect’s telephone technical support staff answered questions when problems arose. (See Figures 3 & 4)
Figure 3, Jonathan Payton stands in front of the new finishing line control
cabinet which includes a DL260 DirectLogic PLC, 8 Durapulse variable
frequency drives, and all the associated control equipment. The entire
design including software was installed during their 3-week shutdown.
Figure 4, The 15” C-more touch screen operator interface brings all the
controls of the finish line to a common point on the machine and includes
set-up screens, maintenance screens, operations screens as well
as diagnostics.
The solution has been a great success. The mill saved nearly $40,000 compared to the bids received, and now the control system is now largely software based. Operators have much more control of the machine, including setup parameters of dry cans and dancers, line speeds, trimming capabilities, as well as some fault indication and maintenance screens. New functions or features can also be added, as they continually refine the process to improve productivity.
On a second project, Mount Vernon retrofitted the legacy control system for a re-beamer in order to improve performance and flexibility. The re-beamer is a speed-controlled center winder which winds yarn from several section beams onto a single-loom beam prior to weaving. The winding speed requires constant adjustment to maintain a constant yarn velocity.
The original control design for the re-beamer featured manual controls (pushbuttons, pilot lights, and meters) on the operator station and a DC drive to wind the spool. With dozens of these machines throughout the facility, not only was it more difficult to obtain replacement parts for outdated equipment, but it was also difficult to make changes to the machines, operator interfaces, and control system.
The re-beamer is now equipped with a DirectLOGIC DL06 PLC, a Durapulse AC variable frequency drive, a proximity sensor and a C-more operator interface panel. Because the outsourced PLC program never worked correctly, it was scrapped and rewritten in-house. This allowed placing more parameters and adjustments at the operators’ fingertips. Additionally, operators continually suggest improvements to the process or machine, and now system programmers are able to act on their inputs, and use the software based control system to streamline the process. (See Figures 5 & 6)
Figures 5 & 6, An operator works the rebeamer during production.
The move to a software based C-more has given the operator more
capability to change parameters during production.
Mount Vernon Mills continues to retrofit additional control systems as time and budgets permit. The control solutions put together with AutomationDirect equipment have provided quite a cost savings over alternative solutions on the initial purchase. Changing the controls to software-based HMI and controls also provides the flexibility to easily make changes and improvements to the line.
Control engineers at Mount Vernon Mills agree the free technical support from AutomationDirect is the best they have ever used. They also feel the quality and service of AutomationDirect products to be comparable to more costly products purchased from previous suppliers.
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Natural Gas Reclaimed from Expired Wells
By Glenn Erickson
Expert Automation Design, Inc.
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Natural gas can come from wells specifically drilled to reach gas trapped in pockets beneath the surface of the Earth. These wells produce huge quantities of gas which can be piped directly to distribution centers and then on to consumers. Some wells produce a lower-quality gas which has to be processed to remove unwanted components before it can be sent to the distribution center. This separation process can be expensive, and is therefore only used on mass-producing wells where the cost can be justified.
But that is not the only viable source of useable natural gas; thousands of exploratory and low-yield oil wells have been drilled over the years. Once the “cheap” oil is extracted, these wells are typically capped off, becoming a statistic on a map. Even good oil wells, once they are “used up,” are often capped. However, they are not forgotten.
Many of these now-unused oil wells contain natural gas. The quantity and/or quality of the product from these wells may be too low to be commercially viable by conventional means, but one oil company recognized a need to turn these wells into valuable energy sources for America.
To extract useable natural gas from these wells, this company used a technology that has been known and applied to many processes: Adsorption. In this process, molecules “stick” to a media, forming a film of the molecules. This is not to be confused with the Absorption process in which molecules are actually drawn INTO the surface of the media. Both processes are helpful in thousands of applications, using solids and liquids to purify products.
The company chose to use granular carbon as their adsorption media because of its natural affinity for hydrocarbons. The carbon is contained within a steel pressure vessel. A pair of these pressure vessels allows the system to alternate between the Adsorption and Desorption portions of the cycle.
One vessel is connected to the well and gas is allowed in under pressure, while at the same time the other vessel is evacuated. The carbon in the vessel connected to the well attracts methane and other hydrocarbons, while ignoring nitrogen and other non-hydrocarbon gases. Once the media is saturated with molecules, the vessel is disconnected from the well and placed under a vacuum. During this process, the other vessel is connected to the well to take its turn at adsorbing methane.
Figure 1, The picture above is of the system on site in Oklahoma.
The two large white towers are the adsorbers. The smaller tower
is a dehumidifier. The old tanks in the background are the
remains of the decommissioned oil facility.
Figure 2, This is a photo of the entire system. The small white house
to the left is the control center. The generator on the right runs on
gas from the well.The purified natural gas is stored onsite in a huge
propane tank. The connection to the gas distribution pipeline is
behind the white tanks.This system is designed to run autonomously
once started. The only human interaction needed is for someone to
check on the generator’s engine oil periodically.
Placing the vessel under vacuum “de-sorbs” the hydrocarbon molecules from the granulated carbon, which are then pumped to a temporary storage tank. This cycle of adsorption and desorption can occur thousands of times before the granulated carbon needs to be replaced. The purified natural gas is stored onsite in a huge propane tank.
Any hydrocarbon molecules that are not adsorbed are flared off by a small pilot flame to keep them from escaping and becoming greenhouse gases.
The company built a demonstration plant to test their theory and ran it manually until they had what they considered to be a commercially viable process. It was at this point that they turned to AutomationDirect to help them find a company to automate a larger adsorption plant. From AutomationDirect’s list of system integrators, Expert Automation Design Inc (EAD) of Seminole, Florida, answered that call.
Figure 3, This is a picture of the control enclosure just after
completion. It is a simple system using an 06 PLC with various
analog functions, and Ethernet for the touch screen, and for
future Internet communications.The small black box in the
lower left corner is a phone dialer for alarms and system
status. Internet is not available in the area.
The oil company needed a repeatable sequence of operation, with parameters they could adjust as they improved the process. EAD developed a simple system using a DirectLOGIC DL06 PLC with various analog functions, C-more touch panel and Ethernet for both the touch screen and future Internet communications.
Figure 4, This is another view of the enclosure showing the 6-inch
C-more touch screen. The next system will use a larger screen.
Throughout the design process, ease of use was vital; the idea was that anyone should be able to start the system, or shut it down, with little or no training.
All critical values and status are available on one screen. The STARTUP and SHUTDOWN buttons lead the operator through a series of screens to properly start up and shut down the entire system. Status messages appear below the digital displays.
In early summer 2008, EAD installed the system in a refurbished valve building at the site, and flexible conduit was run to junction boxes around the plant. The entire installation of all electrical components took two and a half days. The gas-powered generator was converted from 208 volts to 240 volts. After various challenges, from pressure regulator issues to a lightning strike which destroyed the PLC, now the plant came online. Once up and running, it operates autonomously around the clock. The only human interaction needed is for periodic routine maintenance on the pumps and generator.
Figure 5, Here is a shot of the screen in action onsite. The interface
is as simple as it looks. The idea was that anyone could start the
system up, or shut it down with little or no training. All critical
values and status are available on this one screen. The STARTUP
and SHUTDOWN buttons lead to a series of screens that walk the
operator through the proper ways to startup and shutdown the
entire system. Status messages appear below the digital
displays. The alarm banner is at the bottom of the screen.
Once this process has been perfected, many more of
these systems can be produced to help meet the energy
needs of America.
EAD has worked closely with the oil company to remotely troubleshoot control issues and add upgrades. They used DNloader to download PLC program changes sent to them. They have become adept at using the C-more software to download supplied changes or to make small changes themselves.
For more information, visit: www.eanda-technical.com.
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