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Are there any fuel oil handling systems that don’t need return pumps? Are there any advantages to not having return pumps?  While it is true that I have worked on system designs and executions that have not included return pumps, my general answer is “no,” there are not any advantages.  And there are many different functional reasons why, especially within Mission Critical and First Response handling systems.  The purpose of this white paper is to list several different uses for return pumps under various circumstances, and to demonstrate how every single installation can benefit from them.

 

We all know that return pumps are great for keeping things under control, even if humans seem determined to find a way to spill fuel—running supply pumps in “hand,” or opening valves that should remain closed, and preventing a day tank overflow.  This is the most basic function of a return pump, and by far the most popular reason for their inclusion in both older and more modern designs.

 

FUEL RETURN:  Sending fuel from a day tank, to a main tank

Fuel return is a return pump’s most basic function.  During typical, normal operation, the return pump will be a lonely piece of equipment, but will also be one of the important safety features within the entire fuel oil handling system (FOHS), potentially saving very significant environmental and financial damages.

 

On many basic systems, the return pump will only activate when a “high” level float switch is activated, or similar signal, from a Controller.  An improvement is to have the return pump interlocked with a “high” level switch, which will start the return pump even in the event the Controller is offline or disabled.

 

Be sure to size the return pump appropriately to the application.  Calculate the highest possible rate of fuel entering the day tank.  On multiple day tank systems, this may mean the highest flow rate possible from all supply pumps running simultaneously, while filling that one particular day tank, and no others.  The return pump should be sized at a significantly higher rate than that potential high-flow rate.  How much higher will depend on pump type, available flow rates, etc., but should be 150-200% of the highest flow rate possible from the supply pumps.

 

 

INSPECTIONS AND REPAIRS:  Emptying a day tank for repair or replacement

What if you find fuel in your day tank’s secondary containment?  After looking for the usual leaking suspects, such as a threaded connection, weld, valve, etc., you may come to the conclusion that your primary tank is leaking.  Whether you intend on inspecting the tank, repairing or replacing it, you will need to drain it first.  But, if you have only a top/side-mounted overflow, how do you get the fuel out?

 

A return pump makes this process much faster and less messy, sending the good, clean fuel exactly to where you want it—back into the main tank.  You are also eliminating potential problems with big, messy barrels, which will contaminate the fuel and cause you to dispose of hazardous materials, increasing the hassle—not to mention the expense—even more.

 

 

FUEL FILTRATION:  Cleaning ALL of the fuel, not just the fuel in the main tank

One of the most common reasons for emergency generators to fail to run is bad fuel.  The best way to prevent bad fuel is to filter it.  ALL of it.  This means polishing the fuel that is trapped in supply lines, return lines, and day tanks.  Generators get their fuel directly from their day tanks, but most fuel is only polished in the main tank!

 

Return pumps are great for circulating fuel.  Modern control systems can be programmed to run polishing sequences, including activating return pumps (and supply pumps) that will circulate the fuel through the day tanks and allow it to be cleaned at the main tank(s).  Running a day tank “turnover” sequence, in combination with a filtration/polishing sequence, ensures much cleaner fuel throughout your entire fuel system.  The best generators on Earth won’t run on bad fuel!*

 

*ALL Mission Critical facilities should be on a strict fuel filtration and polishing regimen (Please look out for other white papers about Filtration from Preferred Utilities).  In fact, any facility that requires a backup generator of any type has a responsibility to ensure, to the best of their ability, that the generator runs in an emergency.  That’s what they’re there for!

 

 

THERMAL MANAGEMENT:  Decreasing fuel supply temperatures for generators

Generators use diesel fuel oil not only for internal combustion, but also for cooling the engine’s injectors.  Less than half of the fuel that the generator draws from the day tank is actually used for combustion; the remainder of the fuel is returned to the day tank by the engine, and at a higher temperature.  As continuous running creates a continuous fuel temperature increase, this can adversely affect the performance of the generator, up to, and including, generator shutdown.

 

There are two main contributors to overheating a day tank’s fuel:

  1. Ambient temperature.  Perhaps the day tank is outside, or on a rooftop, in a warm climate, or all of the above.  If the fuel in the day tank is already at 95 degrees F, for example, it’s going to rise fairly rapidly when the generator engine starts.  Unfortunately, in places like California, many power outages occur during the hottest days of the year, due to excessive demand on the grid.
  2. Day tank size versus generator engine size.  A large generator engine paired with a small day tank will increase the day tank fuel temperature quickly, regardless of any other environmental conditions.  Local, state, or national code may inhibit the installation of larger day tanks.

 

Return pumps can assist in decreasing fuel temperatures for generators under both scenarios.  By simply circulating the hot fuel out of the day tanks, and replacing it with cooler fuel from the main tank(s), the generators will continue to run, and run more efficiently.

 

This fuel circulation can be automated.  The day tanks can be equipped with Resistance Temperature Detector (RTD) probes, which will monitor the day tank temperature.  When the day tank temperature reaches a pre-determined threshold, the RTD will signal the master control system (“Controller”), which will start a day tank cooling sequence.  We sometimes refer to a day tank cooling sequence as, “level bouncing.”  A level bouncing sequence would look something like this hypothetical example:

  1. RTD reports temperature threshold met on Day Tank 1 to Controller.
  2. Controller activates Day Tank 1 Return Pump.  Day Tank 1 begins to pump out.
  3. Day Tank 1 reaches “Supply-Pump-On” lower level, which creates a Call For Fuel.
  4. Controller turns Return Pump off.
  5. Controller activates Supply Pump, and opens Day Tank 1’s inlet valve.
  6. Supply Pump fills Day Tank 1.
  7. Day Tank 1 reaches “Supply-Pump-Off” high level.
  8. Controller deactivates Supply Pump.
  9. RTD monitors temperature, and…
    1. RTD reports temperature threshold met on Day Tank 1 to Controller, and sequence repeats… or…
    2. RTD reports temperature acceptable.  No action occurs.

Return pumps are useful for far more than just pushing fuel back to a main tank.  They are an integral part of any system and do not only save us from a messy cleanup and a lot of explaining, but also enable us to truly and completely clean a system, cool a day tank, or just do a more thorough inspection.

 

For more information, or if you have any questions, please contact:

 

Lee Carnahan

District Sales Manager, West

PREFERRED UTILITIES MFG. CORP.

209.890.9993 cell

LCarnahan@preferred-mfg.com

 

A linkageless control system uses a burner with individual servos to control fuel and air ratios, and provide more savings to the end user. This technology can cut boiler room costs and solve end-user headaches. Here are three reasons to choose linkageless controls:

  1. Higher efficiency: O2 levels may fluctuate, but will always return to position of highest fuel and electrical efficiency. In addition, turndown is often improved resulting in less cycling of the burner.
  2. Monitoring and communication: the system communicates via Modbus and reports on all functions. The main module monitors the positions of all fuel- and air-control devices. Any positioning error shuts the burner down safely.
  3. Automatic adjustments for ambient air and fuel changes: Linkage systems can cause major problems for technicians. Once all the linkage is set, the ambient air density may change, throwing the system off. In addition, instead of system readjustment every time there is a fuel switch, the positions of all servos are programmed and independent. This means that the system adjusts automatically to fuel/air ratio changes as well as fuel changes.

In a world of high electric and fuel costs, this technology is indispensable to the modern boiler room.

 

Preferred’s Fuel Oil Handling and Boiler Control Cabinets now have California’s OSHPD Seismic Preapproval. This certification, required by the building code for all hospitals and large nursing facilities in California, verifies the integrity of manufacturer’s equipment and components in event of a seismic disturbance, an earthquake. Through “shake table testing,” Preferred’s boiler and fuel oil handling panels have received the certification that proves its functional ability survive an earthquake and keep your facility running.

 

Top tier American college chooses Preferred Utilities as their partner in a major burner and controls retrofit project on their existing (700 hp) Johnston Boiler. With the installation of the dual fuel Preferred Utilities API-InjectAire burner, the college will reduce its electric consumption on this unit by more than 75% while increasing combustion efficiency by more than double.

With the new ability to have Low NOx 10:1 turn down on natural gas and 8:1 turn down on oil along with precise draft control, and O2 trim, greenhouse gas emissions will be significantly reduced along with wear and tear on the boiler.

We manufacture in the USA and provide single source responsibility for burners, fuel trains, combustion controls and factory start up.

 

Preferred is happy to announce Simoneau Sterling Midwest is Preferred’s new exclusive representative for Minnesota, Iowa, North Dakota, South Dakota, and Wisconsin. Todd Moore, now with Simoneau Sterling Midwest, has been a valuable partner to Preferred over the years. We look forward to working with Todd on many more great projects, supported by Simoneau Sterling’s engineering and manufacturing.”

 

The PCC-IV loop controller is the next generation of Preferred’s loop controllers AND upgraded technology for the entire industry. The PCC-IV is more flexible, has extensive memory, and not only replaces the Preferred PCC-III, but also can replace the Siemens Moore 352 and 353, obsolete and no longer supported starting October 2017.

Preferred Utilities’s controls are just that- preferred. Consider a case study of a longtime PCC controls customer:

Preferred Utilities has been supporting this facility in New York since 1988 with our PCC II and III loop controllers. This site installed one PCC-IV and is now considering this next generation of upgrade, the PCC-IV, in their plant with four (4) 50kpph boilers, each with steam, gas, and oil flow meters.

In 1988, the facility installed 16 PCC-IIs and 5 control panels, plus field instruments for a burner/controls upgrade. Almost 10 years later in 1997, they updated the system with the purchase and installation of 17 PCC-IIIs. In 2002, they decided to upgrade again and add O2 trim. Satisfied with the Preferred product, they installed 21 of the PCC-III units.

Now, in 2017, the plant installed a PCC-IV in parallel with one of the PCC-III controls to observe the performance and is considering upgrading the rest of the PCC-II and PCC-III controls. With the auto-converting functionality of the PCC-IV, the existing PCC-III programs can be re-used without modification and re-programming.

Preferred Utilities is pleased to offer generations of quality products that age gracefully and come with a pledge of full service support and solutions for upgrades in the future.

PCC-IV Loop Controller Front

PCC-IV Loop Controller internal

 

 

 

A New Jersey paper mill came to Preferred Utilities recently needing a quote for a new burner for their 1961 Preferred Utilities Unit Steam Generator. What is wrong with their existing Preferred burner? Nothing. The plant is being forced to convert from No. 6 heavy fuel oil to natural gas.

Will their next burner last 56+ years? Maybe. It depends on who they buy it from.

Note, Preferred still had the documentation on the existing burner and boiler. But we had to go to 49 year Preferred veteran engineer Ricky Erickson to find it.

This plant needs a Low NOx burner that meets the emissions regulations in New Jersey. Preferred designs and builds burners that can meet the strictest regulations, and provides configurable NOx settings, “future-proofing” them against lower emissions requirements that states may adopt in the coming years.

Built for the environment. Built to last.

 

 

Last summer a facility in Texas spilled 3,500 gallons of diesel fuel intended for one of their emergency generators. The fuel was pushed up through a day tank vent, ran across their parking lot, and into a pond adjacent to their property. The clean-up team recovered about 2,100 gallons of fuel out of the pond, but at a cost of about $300,000.

I was called to the site two weeks after the spill and took these pictures of the pond. It’s amazing how resilient nature can be in Texas. The only damage I could see to the pond was browned grass below the waterline. Now, ten months later, the pond appears to have fully recovered.

 

The generator fueling system for this facility was installed in 2013. From an inspection of the day tanks, all the instrumentation and safety devices met the required NFPA and local fire codes. However, I did not recognize the systems integrator who did the PLC controls. I suspected there was an error in the PLC program exacerbated by a system design that didn’t anticipate something going wrong.

 

The facility owner brought in a couple of sharp corporate engineers to autopsy the existing controls. They found errors in the PLC programming logic. A level sensor failed, showing a low fuel level in the day tank, so the PLC controls energized supply pumps to re-fill the day tank from the main storage tank. With the level sensor stuck, the PLC controls ignored all the other instrumentation indicating the tank was full, continued pumping fuel, and quickly overfilled the tank. The facility engineers thought the system started pumping fuel at about midnight. Facility staff coming on duty at 7 a.m. smelled diesel fuel, noticed the fuel on the ground, and shut off the pumps.

 

At first glance, the control sequences for diesel generator fueling systems are not terribly complicated, so local systems integrators are often hired to provide controls for fueling systems. However, to ensure fuel is always available to mission critical emergency generators, and fuel spills are prevented, the Preferred engineers—who specialize in the design of generator fueling systems—try to anticipate every likely failure mode:

 

–What happens if a level sensor gets stuck?

–What happens if an analog transmitter fails and produces 0 milliamps?

–What should the controls do if a pump fails to prove flow?

–What happens if there is a break in a fuel line, or a tank starts to leak?

–What happens if an operator manually energizes a fuel transfer pump and then goes home?

 

After supplying so many fueling systems over the years, all of these failures will happen. Regardless of a component failure or operator error, fuel spills are still unacceptable, and the generators still need fuel.

 

I did boiler controls for twenty years before learning how to design and commission fuel handling systems. NFPA boiler code dictates all the safety devices and sequences required to operate boilers. As a result, at least three separate devices must fail to run the water out of a boiler, or overpressure a boiler. NFPA code for fueling systems is much less specific. In fact, the fuel system that caused the spill at this facility didn’t violate any NFPA fuel handling codes.

 

In the end, this facility’s Preferred installer and consulting engineer commissioned the new Preferred fuel handling system controls. Commissioning is the process of simulating all the “What happens if…” scenarios described above and verifying the fuel system responds correctly to all imaginable upset conditions.

 

It’s the last thing we do on every fuel handling project.

David Eoff, BSME, MBA

Preferred Utilities, National Sales Manager

 

What happened the last time your house lost power? That email you were writing might have had to wait an extra half an hour, and your refrigerator might have warmed a few degrees. At most, ordinary power outages represent a minor annoyance to the home or office.

The situation is different at the massive data centers of the world. Amazon now sells over 600 items per second, and their systems are designed to accommodate up to 1,000,0000 transactions per second. At this scale, a 20 minute power outage at one of the data centers powering its store could cost Amazon millions of dollars in lost revenue.

To avoid this sort of catastrophe, the world’s big data centers strive to meet the Uptime Institute’s “Tier-Standards,” specifying various levels of guaranteed data processing availability, reliability, and redundancy. Meeting these standards requires avoiding single-points of failure — all components must have redundant backups.

One of the most critical components, of course, is the power supply system: without power, the flow of data grinds to a halt. Although massive data centers pull their power from the public electric grid, they must have redundant systems of backup power ready to go. Stored power in batteries is important, but the real backup system is the diesel generator.

Managing the reliability and redundancy of their generator systems is a significant challenge for data centers. It’s an unfortunate reality that components break and systems fail tests. At many data centers, the fuel system supplying the generator will have components from a legion of vendors, not one of whom will understand (or take responsibility for) the whole system. This can make troubleshooting routine systems failures a nightmare.

Working with a company that provides a fully integrated system is essential – from the fuel tanks and pump systems to the monitoring devices and control systems. Therefore if a problem arises, data centers have a single support call to make. A single source contact will understand how the pieces work together and can quickly solve problems. It’s the difference between working with a parts manufacturer with a few engineers on staff, and an engineering design firm that manufacturer’s the parts.

At Preferred Utilities we specialize in fuel systems—it’s what we do all day, every day—we pride ourselves on designing reliable systems that reduce the need for support calls in the first place. Data center engineering teams are generalists and great at looking at the big picture, so when it comes to fuel systems, they often aren’t able to immerse themselves in the details the way our engineers do. We know the code compliance specs, how to make sure the tank size is correct, and how to optimize virtually any scenario to help data centers at all Tier levels to keep the their fuel, power, and data flowing.

If your company or industry requires this kind of technical expertise, you can reach Preferred Utilities Manufacturing Corporation at (203)-743-6741. We are dedicated to your success. People. Products. Results.

 

RFO-headerDiscussions of sustainable energy don’t often include food flavorings. However, the same process that creates liquid smoke—the stuff you can buy at the grocery store to add a smoky flavor to just about anything—can produce liquid wood, a very environmentally friendly fuel.

You may not have heard of liquid wood because, until very recently, it was quite difficult to burn effectively. Preferred Utilities Manufacturing changed this.

Liquid smoke is part of a family of products whereby wood is converted from a solid into a liquid. Wood pulp is heated in the absence of oxygen during a process called pyrolysis. This produces bio-oil—or liquid wood.

Unlike petroleum or natural gas, liquid wood fuel is a 100% renewable resource: the wood used to create the fuel can be balanced by replanting new trees. Liquid wood is also carbon efficient because the replanted trees offset carbon emissions, which eliminates the need to purchase separate carbon offsets. As a result, liquid wood is 81 percent more carbon efficient than natural gas, and 88 percent more carbon efficient than petroleum.

Once it’s being properly fed to the burner, liquid wood behaves pretty much just like traditional fuel oils. This means that existing boiler equipment can be retrofitted for use with liquid wood, dramatically decreasing conversion costs compared to other biofuels.Green Oil

So why haven’t we seen the widespread adoption of liquid wood as a fuel oil? After all, the basic chemistry isn’t new—liquid smoke has been around for more than 100 years. Ensyn, an Ontario biofuel firm, has become adept at producing competitively priced liquid wood fuels, but very few companies have been able to offer reliable systems to burn these fuels, and none have been successful in the marketplace—until now.

Ranger-Brochure-ClipOne of the keys to burning liquid wood is the pump system that delivers the fuel to the boiler. Liquid wood has to arrive in the boiler at much higher and more specific pressures than natural gas or petroleum, and because it is highly acidic, the pipes must be high-grade stainless steel. This all requires advanced pumping and monitoring equipment, combined with the engineering chops to put the whole system into place. That’s where Preferred Utilities shines.

As a hybrid engineering/manufacturing firm, Preferred is uniquely equipped to devise and implement customized solutions to help commercial and residential properties including universities, colleges, hospitals, and more convert their boilers to liquid wood. Compared to other biofuels that can’t be retrofitted to existing systems, such as wood chips or pellets, the logistics and upfront investment of converting to liquid wood for heating fuel is quite reasonable.

But handling the fuel is one thing. Burning it? Another thing entirely. We’re talking about a substance that is 25% water with the consistency of lemon juice. Burning it effectively presents a significant challenge. That’s why Preferred Utilities developed the Ranger Combustion System. As of May 2017, Preferred Utilities burners are the only known burners capable of effectively and reliably firing liquid wood. There are several installations in Ohio, Vermont, and Maine currently burning this fuel with Preferred Ranger Burners.

Ranger,-Open,-Vignette-[web]

Liquid wood also presents an opportunity to go green quickly. It can take years to transition to carbon neutral, but a liquid wood conversion can be completed in a matter of months. We have found that in many cases this extraordinary fuel source can reduce carbon emissions by about 80 percent. For more information about the potential of using liquid wood at your establishment, contact Preferred Utilities at (203) 743-6741.