The need for proper chemical reactions continues as diesel engines further develop into more effective and economical power sources for the wide range of products used in hole drilling. These days, it’s important that things proceed properly in the after-treatment system, not just the combustion chamber. This is important on a wide range of the new engines, but primarily those over 75 horsepower.
That’s because the SCR (selective catalytic reaction) constitutes a whole chemical system on its own that, like the burning of diesel fuel, requires a proper mix of ingredients to ensure that each drop of respective “fuel” is properly consumed. This ensures that maximum performance and economy are achieved.
With effective selection of the right ingredients and judicious adherence to correct procedures, contractors can ensure that what enters at the front end does its job, but also that what comes out the back end is not offensive.
Foraging About in the Early Days
Burning is a chemical reaction that significantly changed the lives of the earliest humans on earth. Also known as combustion, it is essentially the combining of a fuel with oxygen. Think of the fact that one of the two requirements — air — was all around and no cost to utilize. It’s truly a blessing for all.
Things on the air side for engines have not changed that much. We still rely on it, though we do sometimes force more of it into engines these days. But engine fuel requirements have gotten more demanding recently as we’ve figured out how to harness the power of combustion to do actual mechanical work. Today’s diesel fuel is much more refined and particular — a far cry from the product that was, initially, something of a castoff from the distillation process for petroleum pulled from the ground that generated the much-desired gasoline. It’s important to remember this in order to minimize damages that can occur from its careless usage and handling.
One recent significant aspect was the stripping of excessive sulfur in order to allow usage with the impending catalyst systems used for reducing emissions. This was done some years back, and ULSD (ultra-low sulfur diesel) offered these days has an upper limit of 15 ppm (parts per million) sulfur. The initial troubles with lowered pump lubricity due to lower sulfur were promptly addressed with an added lubricity requirement. So, no worries there, despite what is sometimes suggested.
The basic characteristics of diesel regarding such things as cloud point remain the same, and one must pay close attention to temperatures to ensure that gelling will not occur. Products are also available to treat diesel in order to minimize such effects.
Another important concern is the “bio” aspect — the use of diesel with a partial or considerable bio-base rather than a pure mineral base pulled from the ground. The shelf life of the fuel changes, whether it’s a small amount — as in, say, a B5 blend (5 percent bio) or even more, once this vegetable product is added. It behaves the same as any food product you might use in the kitchen.
The sensible approach is to minimize or eliminate the use of any bio blend if said fuel will not be consumed in a reasonable amount of time. While a little bio won’t be a problem for most products used on the drilling jobsite, it’s just not a good idea to have any in place for, say, a standby generator set. For something like that, the fuel is just ripe for turning bad because it’s not being consumed.
For those who are the savviest to what they’re buying and consuming, realize that some states allow blending with bio to a certain amount with no specific need to advise the purchaser. If you’re buying fuel and looking for a nutrition label, it will be on the snacks in the store and not on the pump. Take the time to learn what is offered locally.
Contamination is a final significant concern for this sweet diesel fuel offered these days. This might include particulates, crud or any number of solid things that might have found their way into the tank. This is just not acceptable — especially with today’s extremely high injection pressures and tight clearances, where even the smallest of particles can do considerable damage. Assuming that one is purchasing “clean” fuel, and it doesn’t hurt to ask a few questions of the supplier to confirm this, it is critical to practice cleanliness all along the way, so the possibility of contamination is minimized. Now might be a good time to have a thorough review of all fuel handling practices to ensure both an understanding of this need by all, and that proper habits have been fully adopted. By all.
If one has been prudent in the purchase and distribution process, that first chemical reaction of each precious fuel molecule reacting with an oxygen partner will continue for many hours and years of engine operation.
A Pleasant Ending for Things
Most likely not witnessed by any of the early inhabitants first discovering combustion would be the second chemical reaction of engine concern these days: the conversion of NOX from the exhaust gases into nitrogen and water. It’s interesting to note that it’s an “external” process — like a fire burning — in that the reaction is not accomplished in an enclosed space like the combustion process of an internal combustion engine.
Naturally, there are some challenges in doing this effectively, as engineers are not able to design components with the inherent closed spaces required to keep things together and ensure the absolute best reaction between the involved chemicals. But they’ve done a good job of it, and conversion rates are quite good. An emissions-compliant engine using this technology will have very low levels of NOx exiting the back end.
The DEF (diesel exhaust fluid) used in this process, interestingly, is itself “bio” based. It has origins in the agricultural world as an ammonia-based product. But it’s stable overall. If it freezes, it will thaw out. It’s simple to buy, as there’s only one variation.
But — and this is very important — one must be careful to avoid certain materials that will readily react with it. Stainless steels and plastics are acceptable, and if one transfers the fluid directly from the initial container, the chance of troubles won’t come into play. The essential thing is to avoid contact with other metals. Trace elements of those metals that come loose will promptly deposit on the catalyst, damaging it and reducing its useful life. If a funnel is needed for a particular machine to be topped off, dedicate a proper funnel for this task only.
Drum roll — or perhaps tote or jug roll, depending on what container size your DEF comes in — the most important thing, again, is to ensure cleanliness. It’s certain that you’ll be receiving DEF in a clean state, as it is readily produced in clean conditions and then transferred to that final dispensation container with, typically, no intermediate steps. In this respect, it’s a bit unlike diesel fuel, which may be transferred to various containers a number of times after it’s refined. So, just be careful when you go to use DEF, so that all the work to that point does not go to waste.
The result will then be that, when the precious fluid is sprayed into the exhaust, it will partner with a precious NOX molecule and not coat that expensive catalyst used in the SCR system with unwanted materials, leading to its early retirement.