Posts tagged hot oil

The Evolution of Asphalt Heating

Road. (n.) A wide way leading from one place to another, especially one with a specially prepared surface that vehicles can use.  “If you don’t know where you are going, any road will get you there.” Lewis Carroll

The first great roadbuilders, and engineers, were the ancient Romans, and parts of their roads survive to this day, over two millennia later. In the interim, the prepared surfaces of engineered roads have been made of mud, clay, brick, stone, and even wood block. Yet, for over a century now, by far the most common durable road surface has been the familiar black cement-and-aggregate mixture known as hot-mix asphalt. Other English-speaking parts of the world know it as bitumen, or macadam.

Ancient Roman road of Tall Aqibrin

Ancient Roman road of Tall Aqibrin

This asphalt, first mined from pitch lakes on the island of Trinidad and similar deposits around the world, was originally mixed with gravel by hand labor in large metal trays placed over direct fire. Hard, hot work. As this natural asphalt became replaced over the years with an engineered formula derived from crude petroleum, both the heating process as well as the mixing technology evolved rapidly. Early mixers were adapted from the rotating drums used for cement mixing.

The earth and its inhabitants (1894) (14579852357)

Asphalt Lake, Trinidad. 19th Cent.

  And by the 1920s or 1930s, some asphalt producers, supplying material for both roadbuilding and for other uses such as roofing and pipe-dipping, had begun to use indirect heating to improve the uniformity and consistency of the end-product, as direct heat could be difficult to control. A 1931 technical article in The Journal of Industrial and Engineering Chemistry mentions steam, diphenyl vapor, and hot oil among the heating media already in use for indirectly heating asphalt tanks.

0122 Long

Hillside Roadcut, Asphalt Paved

 The evolution continues to this day. The hot oil that those pioneers used back in the 1930s to heat asphalt tanks was a lubricating-oil base stock, designed not for heating but to protect metal surfaces and extend the life and improve operation of rotating equipment. These days, modern heat-transfer fluids are engineered specifically for high temperature service, and are derived from a variety of chemical families for rugged service, long life, and resistance to thermal and oxidative deterioration.

Asphalt Plant, 1930s

Heating Asphalt , 1930s (Img. from ind.gov)

The heating equipment itself has also evolved a long way from those simple heated trays stirred by hand with long metal hoes. In the 60s producers moved beyond hot-oil heated asphalt plants, adding surge bins and storage tanks to allow more flexibility in meeting variations in demand. Innovators continued to develop other ways to extend the workability time and distance range of the product going out of the plant hot and ready for roadbuilding. Today, information systems, and advances in integrating computer systems into testing, supply, heating, environmental controls, and logistics are adding a whole new level of sophistication to asphalt plant operations.

Paratherm—Heat Transfer Fluids and the Asphalt Industry OEMs

Paratherm works together with the asphalt construction equipment OEMs to help their customers, and ours, to keep their systems maintained, up and running, especially when it counts the most.

It’s August, and in North America, the paving season is at its apex for 2016.

Among the equipment specialists in the asphalt-paving industry is Meeker Equipment Company Inc., which manufactures components to upgrade, renovate, and retrofit existing asphalt and ready-mix plants.

I spoke earlier this month with Jeff Meeker, President of Meeker Equipment, about this year’s paving season.

“We hear from our customers that generally speaking the paving season is going very well,” Meeker said. “Certain areas see a bit of trouble, usually related to political issues. New Jersey in particular needs attention to their transportation trust fund, so there’s a slowdown there at peak season.”

“We also see a lot of paving companies reinvesting in their asphalt plants,” Meeker emphasized. “Money that had been sitting on the sidelines is now going back into rebuilding their businesses.”

I asked Jeff for his opinion about of the evolving role of indirect heating, and specifically how the heat transfer fluids can be a key to preventive maintenance in the manufacturing process.

“Well, our people have become more plugged into talking to construction companies about their hot oil in these equipment discussions, and how important it can be for their operations,” Meeker explained.

“These days, when we visit our customers, our people always carry a heat-transfer-oil test kit,” Meeker said. “The plant managers and maintenance men are increasingly realizing the value of their hot-oil equipment, its impact and importance for their asphalt plants. So we can give them a test kit right there and get them started to evaluate the condition of the system based on the oil test results.”

If you’re an asphalt processor, and you’re interested in a fluid analysis kit, you can get one when the Meeker rep stops by. Or, here at Paratherm, there’s an online form you can fill out and we’ll send you one right away. Here’s the link: Fluid Analysis Kit.

 

Note: In researching the text and reviewing images for this post, I came across a very interesting article, in PennLive, about the origins
and history of the PA Turnpike, its abandoned tunnels and planned modern renewal, and the engineering feat that took it through (not across)
Pennsylvania’s Appalachian Mountains.  Here it is— Ghost Tunnels of the Pennsylvania Turnpike.  Haunting photography, too.

What Makes Paratherm Different

How does Paratherm differ? We drew the differences in a 2-minute video — whiteboard style!

And, for those of you who prefer to read, skim, study, and/or critique the written word, here is the voice-over script…

videofrontThe beauty of closed-loop hot-oil technology is that it operates simply and uniformly with little of the maintenance intervention required by alternatives like steam or direct heat. But this low-maintenance characteristic of the technology may leave you in the dark about the operating condition of your application, or what to do when shut down — or slowdown — occurs. Paratherm focuses on keeping you involved in every aspect of the care of your system, from the fluid sale and initial fill, to fluid analysis, troubleshooting and preventive maintenance. Paratherm’s experts will help advise you in the selection of the right fluid for your unique circumstances, and their professional fluid analysis will help guide preventive and predictive maintenance to help improve the system’s operation—and extend its operating life. Unplanned downtime with your application can cost you thousands of dollars every hour that you’re not in production. Therefore, Paratherm utilizes a streamlined logistics flow for fast supply when you need an expedited response. We keep our fluids in stock at several locations throughout the country. When you send us an order, we’re typically able to ship it the same day. When issues with your hot-oil system arise, Paratherm’s Technical Services section is ready with probing questions, and then, troubleshooting tips to help get it working again. You can reach someone by phone for technical assistance or an emergency shipment at any time, including evenings and weekends. At Paratherm, thermal fluid is all that we do, so we have to be the best. For more information on our products and services, simply call or visit our website and fill out our online form.”

To receive a series of emails about Paratherm, and thermal fluid technology in general, visit the Learn About Paratherm page at About Paratherm.

Cleaning Your Heat Transfer Fluid System for Optimal Performance

If you use Paratherm’s high-quality thermal fluids, you probably know the heat transfer solutions they offer, and their many advantages.

But did you also know that it’s important to use a good cleaner in the system to keep it running optimally? Over time, sludge deposits can reduce the flow—and therefore, the heat transfer—in continuously running systems. Using a cleaner prevents this problem and eliminates any possible downtime.

Our Paratherm LC™ System Cleaner Liquid is made to clean your system and work in perfect harmony with our heat transfer fluids, and now through the end of November, we are offering it at a special 15% discount.

Used in mineral oil heat transfer fluid systems, this is an additive cleaner that is introduced in small concentrations—anywhere from three to 10% of the system volume.  You simply add the cleaner and run the system normally for a period of time, while the product dissolves and suspends the deposits. The system continues to run and produce as it normally does, meaning no slowdown or downtime, while its branded blend of additives and detergents dissolve deposits, sludge, and carbon.

Fluid Samples in Jars

Severely Degraded Gelled Fluid, Used Fluid, and New Fluid (L to R)

The process takes anywhere from three weeks to three months, depending on the amount of deposits, after which you simply refill the system with new heat transfer fluid. And if you want to know how the system is running before and after using Paratherm LC™ system cleaner, we can perform a complete heat transfer fluid analysis, providing a full analysis report. If you’re not sure whether  your system is ready for the cleaner yet, the analysis will check its condition and answer any and all questions.

While Paratherm LC™ is the ideal cleaning product for dissolving deposits and sludge in mineral oil-based fluids, we also offer Paratherm AC™ for synthetic/organic-based fluids, and Paratherm SC™ to disintegrate carbon lumps in smaller electrically heated mineral oil-based units.

Not sure which product you need? You can view the line of cleaning products on our website (http://www.paratherm.com/system-cleaners/), or feel free to call us with any questions at 800-222-3611.

Heat Transfer Fluids: A Driving Force of the Asphalt Industry

In the summer of 1970, my first summer job was working on a paving crew.

Back then, the equipment, and the labor used for layering the prep, the screenings, and the asphalt surfacing, was much less specialized than it is today.  We were laying country roads, and an occasional driveway, in rural Chester County, Pennsylvania.  The crew consisted of a foreman, a crew leader, 2 or three drivers  and equipment operators, and around ten laborers.  There was no project engineer as such.  The owner of the company occasionally showed up (he had several working crews at the time) and grabbed a shovel himself.  At 14, I was the youngest, and smallest, and pretty much the least of them, in terms of responsibility and capability. Certainly in terms of experience.  This was a rough-edged, but good humored bunch, and included all sizes, races and ages.

When a stretch of road was prepped and ready, and a dump truck showed up full of hot black asphalt mix, everybody grabbed a tool and pitched in.  It was a controlled, cooperative frenzy to properly, carefully tilt the dump bed, deposit part of the load, shovel, rake and smooth the mix, then steamroll it and move along to the next section.  For twenty minutes, we’d sweat in the summer heat.  Then, until the next load arrived, the pace slowed while screenings were raked and other prep was done, and the fellows chafed each other about their weekend conquests down the shore in Wildwood while chugging ice water from the water jugs the foreman brought along.  If the saltiness of the language was lightened for a 14 year old, it was still a pretty spicy stew.  Sometimes they’d send me off to clean the shovels of the encrusted asphalt cement, with kerosene.

Most Americans don’t think about the roads they are riding on while driving from point A to point B. What they may not realize is that asphalt is literally paving the way for almost every single one of us to get where we need to go. Remarkably, of the 2.4 million miles of paved roads throughout the U.S., 2.3 million of them are paved with hot mix asphalt (HMA).

As of 2009, there were 3,900 asphalt plants producing 360 million tons of HMA, valued at $24 billion.  It’s an industry that’s huge and imperative—over the next 50 years, it’s estimated that it will cost $185 billion to maintain our country’s aging infrastructure, and HMA is going to be a very large part of it. As such an important aspect of our lives, these 3,900 asphalt plants in operation need to be functioning at their best at all times—any delay can be detrimental.

I didn’t know it at the time of course, but around the time when I had my first summer job, hot-oil systems, which indirectly heat varied equipment at asphalt plants, were rapidly replacing inefficient and emissive direct-fired heating, and helping enable plants to lengthen the viable storage time of prepared hot-mix asphalt.  Nowadays, virtually every plant has a hot oil system which heats the asphalt cement—hundreds of thousands of tons of it across North America. Using low-cost oils can cause long-term, serious problems to a system, as well as delays. Such multi-purpose oils are not designed to perform the continuous heating functions HMA plants require. Engineered heat transfer fluids, on the other hand, are specifically designed for continuous high-temperature systems, and will not break down the way multi-purpose lubricating or hydraulic oils can.

This is an industry where calculations, limitations and specifications have become increasingly important.  The practical limit for distance from the plant to the job is around 50 miles, because the insulated trucks will only keep the mix hot and workable for so long. This is why those 3900 asphalt plants are literally peppered all across the country. Which means that those average Americans moving from point A to point B have seen  asphalt plants hundreds of times, and may in fact see them every day without knowing it.  Asphalt plants have a distinctive look with a few telltale visible characteristics; pyramid-like piles of gravel (the aggregate) a slanted conveyor to move the aggregate, and tall cylindrical structures which are either asphalt cement tanks or storage silos.  In 1970, when I worked briefly on a paving crew, you could also see the smoke from the plant’s stacks.  These days, emissions are very well controlled and regulated.

Drawing silhoette of asphalt plant with silos, heater, piles of aggregate

As anyone in the industry knows, this is a seasonal business—in cold weather climates, operation and paving runs from the spring through the late fall, as paving can’t efficiently be done below 40 degrees. This off-season is a great time to maintain the heat transfer fluids and keep them working optimally whereas, during the season, time is of the essence. Keeping a program of routine checks, including a fluid analysis, cleaning equipment, checking insulation, and practicing shut down procedures will ensure that come spring, everything is working perfectly.

Chemical analysis of the heat transfer fluid (usually referred to as “the hot oil” in this industry) is particularly important as the cold season approaches.  If a hot-oil system has been running continuously for several months, and the fluid has significantly degraded due to oxidation or overheating, the heat transfer fluid could actually solidify when the system is finally shut down.   And dismantling a hot oil system is an expensive way to change the oil.  If a cooled sample of hot oil won’t pour, proceed with caution; keep the circuit hot until you consult with the heater or fluid manufacturer.

When our nation’s entire road transportation system depends on the performance of HMA plants, the right kind of heating is essential.