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Category Archives: Special Combustion

 

Pictured: one of two Preferred Special Combustion burners and control cabinets to be installed at an American steel manufacturer in Ohio, and utilized on twin super heaters used in the steel manufacturing process.

The burners, atmospheric element style heaters, use stoichiometric combustion to produce heat input for the super heater. The Preferred UV Self-Checking Quanta-Flame Scanner monitors the flame.

The control cabinets are PCC-IV based, multi-loop controllers combined with the Preferred M-85 Flame Safeguard Controller and Preferred Quanta-Max, a state-of-the-art microcomputer-based burner management system (BMS).

These components work in tandem with the scanner and other safety products on the burner and fuel train to produce safe, stable, and efficient combustion process.

Learn more about Preferred Special Combustion Equipment (PSCE)

 

A high efficiency and very “green” 50 KPPH Packaged Burner System about to ship out to one of the world’s largest privately held companies. 

Preferred Special Combustion Engineering (PSCE) provides a complete package combustion system for new or OEM watertube boiler projects. A complete packaged burner system (including controls) all from one source will optimizes burner to boiler special interface, allows for maximum pre-wiring of the system devices, provides a more complete checkout process, and minimizes field errors and commission time.

These often overlooked factors add up to real dollars saved.

For more information or to discuss your application, contact Brian Sy at (203) 297-4800 or by email at bsy@preferred-mfg.com

 
 

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.

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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.

 

 

 

 

2015 was an exciting year for us at Preferred Utilities. We launched a series of new online engineering tools, we released the new Flexible System Controller (FSC), and we saw several of our engineers published in energy industry trade magazines.

To cap off the year, we attended the Power-Gen International trade show in Las Vegas, NV. The show featured a new 20×20 island booth and a never-before-seen video highlighting Preferred Special Combustion Engineering.

 

Take a look at the video below for an insight into Preferred’s many combustion capabilities:

 

 

Preferred Featured in Today's Boiler

 

The Spring 2015 edition of Today’s Boiler magazine published Dr. Jianhui Hong’s article “NOx Emissions Reduction Strategies.” In the article Dr. Hong explains the importance of low NOx and provides solutions for complying with low NOx emissions regulations.

He explains that “NOx is a term used to include two important air pollutants: NO (nitric oxide) and NO₂ (nitrogen dioxide). These pollutants are sometimes called mono-nitrogen oxides…NOx is a term used to include two important air pollutants: NO (nitric oxide) and NO₂ (nitrogen dioxide). These pollutants are sometimes called mono-nitrogen oxides.”

NOx gases are harmful in a number of ways. Exposure to NOx gases is harmful to human health by irritating the mucous membranes and penetrating the lungs, “causing oxidizing damage to the tissues.”

When NOx reacts with water or water vapor, “it forms nitrous acid (HNO₂) and nitric acid (HNO₃). These acids in the rain can make ‘acid rain.’ Acid rain can damage plants and man-made structures such as buildings, bridges, and outdoor sculptures.”

In highly populated areas, “NOx emissions from combustion processes are primarily in the form of NO. In the air, NO reacts with oxygen to produce NO₂. In the presence of sunlight, NOx can react with hydrocarbons, especially VOC (volatile organic compounds) in the air to form ground-level ozone, which is an important ingredient of smog. The reddish brown color of the hazes hanging over the skies of some major cities comes from NO₂ gas… It can cause irritation to eyes, noses, throats, and lungs. It can even cause asthma and other chronic lung diseases such as emphysema and chronic bronchitis.” NOx can also combine with moisture in the air which “induces changes in phytoplankton and produces toxic brown or red algal blooms (i.e. “red tides”). The algal blooms can cause the death of other plants and marine animals in the water.

Thermal NOx, Fuel NOx, and Prompt NOx create the conditions for NOx emission.

Dr. Hong presented five solutions for the combustion community to reduce NOx emissions.

  • Flue Gas Recirculation “targets the thermal NOx by reducing the peak flame temperature and also oxygen concentration…The use of external FGR increases the requirements for the combustion fan” which “become a significant factor in the overall costs of the burners (including fixed costs and operating costs).”
  • Steam/water injection “works similarly to external FGR. It targets thermal NOx by reducing peak flame temperature and oxygen concentration.”
  • Ultra lean premixing “aims to reduce the flame temperature by staying away from stoichiometric condition. Ultra Lean Premixing, if used alone, has the downside of high oxygen level (up to 9%) in the flue gas, and the loss of fuel efficiency due to the very high excess air.”
  • Air Staging supplies combustion air in two or more stages. “The general goal is to reduce flame temperature, and create fuel rich conditions in the early stages, before the final stage of air is supplied.”
  • Fuel Staging supplies fuel in two or more stages. “The general goal again is to reduce peak flame temperature. This technique is often combined with Ultra Lean Premixing to overcome the efficiency issue of the latter.”

In conclusion, Dr. Hong cites that although NOx emissions can be controlled by the mentioned techniques, “the most cost-effective methods tend to be combustion modifications, especially using low NOx and ultra-low NOx burners.”

Dr. Hong’s greatest contribution to the combustion community is his ability to present solutions for common problems in the industry and the stringent regulations placed on emissions.

Read the full article here.

 

 

Energy Savings Calculator

The Advanced Performance Inject-Aire burner blends the best of both worlds: high efficiency and low emissions. In a day and age where manufacturers compromise quality and effectiveness, Preferred Utilities prides itself in challenging the status quo. We don’t do cheap. We don’t do flimsy. We build our equipment to last—in fact, some of our burners built in the 1960s are still in operation in New York City. That’s dependability.

When it comes to decision time, many customers find themselves struggling to pick between low emissions and high efficiency—but why should you have to choose? As an added bonus, our burners can pay for themselves in just a year’s time.

So just how much energy can your application save with an API Burner?

Download our “EnergySaver Payback v8.3” to find out.

Download: Energy Savings Calculator

 

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Danbury, CT – A boiler system functions as a critical component to the continuous operation of a facility.  The loss of a boiler can cause disruption of operation and significant loss. Thus, it is important to maintain safe, reliable, and efficient operation while minimizing any downtime of the boiler system.

A boiler system consists of many sub-systems working in harmony, such as the boiler, the burner and its control, boiler control including feed water and draft control, fuel oil handling system (if burning oil is required), water treatment, fuel gas booster system (for areas with low supply gas pressure) etc.These sub-systems are sometimes procured from multiple sources.  In order to deliver the safe, reliable and efficient service that the end user expects, it is advantageous to adopt a “full system integration” approach.

Possible Problems

A boiler system in general could have many modes of failures.  Failures in water level control have serious implications on the longevity of the boiler and in safety (the sudden inrush of feedwater to a baked-dry boiler could lead to a steam explosion). Water treatment failures can decrease the longevity and efficiency of the boiler. Boiler operators need to understand these dangers. Among all sub-systems, the burner system is by far the most sophisticated subsystem in a boiler system. The burner system has many modes of failure that require extensive training and/or experience for the boiler operators to fully understand.

When a boiler system is not delivering satisfactory performance to the end user, it is sometimes difficult to pinpoint the exact cause of the problem. The following example is used to illustrate this difficulty. Sometimes a burner makes a low frequency noise, often called a combustion rumble. The rumble could be a nuisance or discomfort to the operators and residents nearby, or could even cause damage to property. Potential causes of the rumble include, but are not limited to:

  1. The burner has poor stability at certain firing rates; or the burner’s window of operation is too narrow. This could be related to the design or manufacturing of the burner.
  2. The air/ fuel ratio is improper due to poor commissioning or lack of maintenance.
  3. The servos used by the burner control may have poor accuracy or repeatability.
  4. The linkage between servos and dampers may be loose.
  5. The system does not have oxygen trim to ensure consistent excess air levels. Any variation in draft, ambient temperature, fuel gas composition, building ventilation (affecting building inside pressure vs. outside ambient pressure), or wind speed blowing on outlet of chimney, can affect the amount of combustion air supplied by the fan.
  6. Lack of draft control.  Severe draft variation may cause the air/fuel ratio to go out of range.  This is definitely a challenge if the system does not have an oxygen trim system; it can be a problem even with an oxygen trim if the draft variation is too severe for the oxygen trim to compensate.
  7. The “acoustic coupling” between the burner and the boiler’s fire chamber and the subsequent space the flue gas flows through.
  8. The fuel gas booster could surge and cause the gas pressure to oscillate, beyond the pressure regulator’s ability to regulate.
  9. The boiler room’s ventilation system could be improperly designed. When windows and doors are shut, a significant negative pressure can develop in the boiler room, causing a drop in combustion air supply and air/fuel ratio.
  10. Fuel gas supply pressure and composition can fluctuate, especially if the fuel gas is from an alternative fuel source, such as land fill gas or, to a lesser degree, digester gas.
  11. Burner components may not work well together. For example, the gas regulator may be over-sized for the flow rates of the burner.

Problems with the Multiple-Vendor Approach

Fully integrated custom controlsWhen the subsystems are procured from many different vendors piece-meal (by the general contractor or the end user) and no engineering firm takes responsibility for integrating these subsystems, it may be difficult to identify the party responsible for correcting the problem. This often results in blame shifting among different parties, ultimately frustration for the end user.

For example: in a piece-meal approach, the burner may be supplied by a burner company, the controls may be supplied by a company that is solely dedicated to burner controls and knows little about the combustion behaviors of the particular burner. The specifications do not call for a draft control or oxygen trim, when in reality one or both of those may be required for the site conditions and requirements. The booster, if there is one for the job, may be supplied by yet another vendor, the commissioning may be done by a contractor, the ventilation system of the boiler room may not have been designed properly to avoid high negative building pressure.  The troubleshooting process itself is further complicated by the diverging interests of the different parties involved.

Sole Source Responsibility

The most important advantage of the full system integration approach is that the integrator must accept sole source responsibility. If the burner system does not perform, the integrator is responsible for correcting the problem. There is no blame shifting among different suppliers.XPlus

A burner system supplier that adopts the full system integration approach is inclined to build a long term relationship whenever it sells a job. The supplier would look at the specific conditions and requirements of the customer, and look for the best solution tailored for the job instead of chasing the latest trendy requirement in specifications. For example, it may be tempting to ask for a 12:1 or higher turndown from the burner system, but can the non-condensing boiler operate at 12:1 or higher turndown without condensation and corrosion problems?  Is 10:1 or 8:1 turndown enough for the job? In another example, does the system require a draft control device to work? Can the burner deliver satisfactory performance without the draft system?

A supplier adopting the full system integration approach would look at total costs of ownership (the fixed costs and the operating costs) for the boiler system, instead of focusing on the fixed costs. In today’s corporate procurement practices, too often the one responsible for buying the boiler system is not the one paying the energy bill, hence there is less incentive to consider the total costs of ownership.

For example, a burner capable of operating at 1.5-2.5% oxygen during the majority of its operation time can lead to significant savings in fuel costs.  If a vendor offers a burner system without use of  oxygen trim, is the burner operating at consistent excess air levels all year round? Does the lack of oxygen trim mean conservatively high excess air levels? In another example, a fiber mesh burner may be used to meet 9 ppm NOx requirements without FGR, but the additional costs of fuel due to the very high excess air levels (typically 8-9% oxygen dry in flue gas) and the costs of replacing filters and fiber mesh combustion heads need to be factored in when purchasing a burner system. In another example, a burner constructed with flimsy, low grade sheet metals may need frequent service and replacement parts, while a burner constructed out of durable steel can provide years of service beyond the normal warranty periods.

The “full system integration” approach requires an integrator to have in-depth understanding and strong product offerings in all of the following areas:

  1. Boiler controls. The boiler controls ensure safe and smooth operation (water level control, burner firing rate based on temperature or pressure, draft control if necessary). It should have the capability to manage the lead-lag control of multiple boilers to ensure the boilers are operating at maximum efficiency.
  2. Fuel oil handling systems (main tank, day tank, pump sets, filtration, leak detection, etc.)
  3. Burners–especially those designed for both high efficiency and low emissions at the same time. The end user should not be forced to choose between high efficiency and low NOx.  High turndown (such as 10:1) helps avoid cycling of the boiler, and low excess air minimizes loss of heat to flue gas. Use of FGR is acceptable, but the incremental costs of running a larger motor due to FGR should be factored in. Advanced designs of burners can achieve mandated NOx emissions with less, little, or no FGR (depending on the NOx levels required).
  4. Burner controls.  The burner must be equipped with the latest Burner Management/ Combustion Control Systems (BMS/CCS) to assure that safety aspects are in accordance with the latest requirements of NFPA 85 and CSD-1. When high efficiency or tight emissions are required,  an oxygen trim system should be included, and parallel positioning or fully metered control should be used in lieu of jackshaft. The combustion control and the servos should be designed to modulate the controlled fluids (air, fuel, FGR etc.) in a coordinated manner.  For example, if the air servo cannot move fast enough to be in sync with the fuel servo, then the fuel servo needs to be slowed down in modulation, and vice versa.
  5. Commissioning and maintenance.  The burner system is commissioned and maintained by qualified service technicians that are knowledgeable about all the subsystems.
  6. Technical support and spare parts. These should be available from nearby locations.

Preferred Utilities Manufacturing Corporation has earned a reputation for accepting single-source responsibility. We firmly believe in the advantages of full system integration. Compared to the piece-meal approach, the benefits of full system integration make the choice clear. If you believe the same way, please contact us about your next project.