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Category Archives: Preferred Instruments

 

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

 

 

 

Boiler Control RetrofitIn conjunction with Puerto Rico representative M.R. Franceschini Inc., Preferred recently replaced an existing flame safeguard and oxygen trim system with the Preferred BurnerMate Universal (BMU) system on a 500 HP boiler at a pharmaceutical plant outside of San Juan.

In addition to oxygen trim, the BMU is controlling the forced draft fan variable speed drive (VSD), and providing first out annunciation of boiler trips. The BMU was integrated with the existing proprietary feedwater control system and all existing boiler limits.Boiler Control Retrofit with BMU

This steam boiler runs continuously on No. 2 oil, which is expensive in Puerto Rico, so the boiler was tuned for the lowest excess air possible at all firing rates to reduce fuel consumption.

In addition to expensive fuel, Puerto Rico has some of the most expensive electricity rates in the U.S. according to the U.S. Energy Information Administration. Industrial users in Puerto Rico currently pay an average of 14.6 cents/kW-hr compared to the national average of 6.54 cents/kW-hr.

Rate hikes averaging 26%BurnerMate Universal have been announced effective in 2017 for the island. With the new Preferred BMU controller, the forced draft fan VSD speed was kept under 30 Hz from low fire to mid-fire, resulting in electricity savings of over 85% compared to 60 Hz operation.

For more information on the BMU Boiler Control System, click here.

 


How much will you save?
Check out the Preferred Utilities Energy Savings Payback Calculator

Ever tried to justify a retrofit project? Now there’s a better way to crunch the numbers. This app will save you time and money. It analyzes your existing boiler and burner system data and compares it against a proposed modern upgrade, complete with energy savings estimates.

The calculation output in this application is extensive. It includes a fuel analysis, combustion efficiency (existing and projected), fuel consumption, electrical consumption, and C02 credit calculations. Use this tool if you are considering a boiler/burner upgrade.

Used for:

  • Boiler retrofits
  • Burner upgrades
  • Control upgrades
  • Energy auditing

Features:

  • Save your work
  • Recall past projects
  • Print your data
  • Compare Preferred equipment

Energy Saver Payback Tool

 
SCADA Preferred Utilities

SCADA System by Preferred Utilities

SCADA stands for Supervisory Control and Data Acquisition system. It is a type of industrial control system (ICS), which is basically a computer system designed to monitor industrial processes in the real world. But unlike other industrial control systems, SCADA systems can compute multiple sets of data over long distances.

The primary benefit of a SCADA system is the ability to see a visual representation of a complex system. This screen allows the user to see what their application is doing at any given time, while also providing increased control over the entire system.

Another benefit of a SCADA system is its versatility. Practical applications of SCADA can be found in HVAC, water treatment, and power generation facilities. Each SCADA system can be specifically configured for a wide variety of scenarios–if you think it up, we will build it.

One of the unique characteristic of a SCADA system is its ability to withstand temperature, vibration, and voltage extremes. This factor allows it to be placed in almost any HVAC or process plant without fear of breakage.

Preferred Utilities started installing SCADA systems in 1982–that’s over 25 years of experience. We’ve installed them on thousands of burners and hundreds of process plants. Today, we lead the industry as a trusted supplier of cutting-edge SCADA systems designed to meet the standards of the modern energy industry.

To learn more about the SCADA system and how we can help you get the right results in your facility, visit the product page here.

 

PUMC_20130213_024

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.

 

Be sure to check out Preferred Utilities’ contributing article to Today’s Boiler written by Robert Frohock, PE.

From 5 Things You Might Have Missed In NFPA-85″

“Reality isn’t always what you’d assume when it comes to boilers, their controls, and their plants. Several lesser-known aspects could prove useful, so take some time and crack the rest of the code.”

You can view the online version of the magazine by clicking this link (page 10).

Robert Frohock, P.E. is the engineering manager for Preferred Utilities Manufacturing Corp. (Danbury, CT). Find out more at www.preferred-mfg.com.

 

By David Eoff

Danbury, CT – In 1964, Preferred Instruments published an article in the Fuel Oil & Oil Heat magazine. During that time, draft controls were used primarily to control excess draft from tall chimneys and lower excess air to conserve fuel. (Heating oil was 25¢ a gallon in 1964!) Additional benefits included more reliable burner performance, reduced burner emissions, and increased safety by tripping a boiler off line if the draft turned positive.

Check out the first page of that article below.

Draft Control, 1964

Draft Control, 1964

Today, draft controls are still common on all types of boilers,  but for very different reasons. Namely, boiler construction. Since then, many more boilers were of brick-set construction, required to be run at negative draft or balanced draft pressure. Because the furnaces were not air tight, the furnace walls were kept cool by a constant stream of cool air drawn in by the slightly negative pressure of the furnace. Allowing these furnaces to “go positive” for even a short amount of time could result in damage to the boiler casing or injury to boiler operators. Boilers made in this era typically had tall stacks to induce a negative pressure (or draft) in the boiler, or induced draft fans. To control the negative pressure generated by a tall stack or an induced draft fan, stack outlet dampers were installed and controlled to maintain a setpoint typically about 0.1” negative pressure measured at the back of the furnace. Then as now, proper draft control was also important for flame stability and maintaining the correct fuel air ratio in the boiler.

There are still many balanced draft boilers in operation that require draft controls for the same reasons they did in 1964. However, even airtight forced draft boilers built today often need draft controls to help stabilize burners using flue gas recirculation for NOx control. Flue gas recirculation is often induced by the combustion air fan. If the stack draft is too negative, the forced draft fan will not be able to induce enough flue gas to meet the required NOx emissions. If the stack draft is not repeatable, the fan will induce varying amounts of flue gas recirculation that will make the fuel air ratio control unstable. Burners utilizing high flue gas recirculation rates, and ultra low NOx burners have narrow limits of flammability and require precise fuel air ratio control. The combustion controller can’t precisely control the air flow through the burner if the boiler draft is constantly changing.

Boilers that operate with excessively negative pressure will draft too much air through the furnace, resulting in poor burner turndown and poor efficiency because excess air cannot be controlled–especially at lower firing rates. When these older boilers are retrofitted with low NOx burners using flue gas recirculation, the high draft condition needs to be controlled because the recirculated flue gas is diluted by fresh air (called tramp air) that leaks through the boiler casing. The diluted flue gas is less effective at reducing NOx. To meet typical NOx guarantees, effective draft controls need to be installed, and the boiler casings often need to be repaired to reduce air leakage.

Boiler construction today is almost entirely different, but draft controls are still required in many applications for mostly different reasons. Boiler combustion chambers now are entirely steel encased and air tight. The burners always include forced draft fans sized to pressurize the burner windbox, the furnace, and sometimes even part of the stack. The boiler and breeching are designed to withstand this positive pressure without the need for cooling air.

Today draft controls are required to accurately maintain draft conditions in the furnace and compensate for changes in outside conditions including:

  • Changes in ambient air temperature
  • Changes in stack temperature as the boiler warms up or changes firing rates
  • Changes in wind velocity blowing across the stack
  • Changes in draft conditions caused by multiple boilers connected to a common breeching.

Precise draft control is required now because we expect the burner’s fuel-air ratio controller to hold excess air levels typically below 15% at high fire to conserve fuel. The fuel-air controller can’t effectively maintain low excess air levels when draft conditions are changing.

Just as importantly, modern low NOx burners are more sensitive than their 1964 counterparts. Ultra low NOx burners are extremely sensitive to draft conditions (and ambient temperature, stack oxygen, phase of the moon, operator’s attitude, etc.) Too much draft can cause the burner to run lean, become unstable, and flame out. Too little draft can cause the burner to burn back into the burner internals and damage equipment. Most burner manufacturers require draft controls be installed with their burners if any of the following conditions are present:

  • Boiler stack is taller than 100 ft. (sometimes 50 ft. is the limit)
  • An induced draft fan is running in the stack
  • Two or more boilers share a common stack

If your applications meets one of the above conditions and you don’t install draft controls, the burner manufacturer will offer little help if you experience burner stability problems during start-up. A typical response will be, “Install draft controls and call us if the problem persists.”

To meet the increasingly demanding requirements of modern low NOx burners, draft controls have become much more sophisticated.

–Draft range transmitters have replaced the diaphragms in direct-sensing draft controllers. This is an important advance because the sensing line and diaphragms in direct-sensing draft controllers were prone to fill with condensation and quit working. Transmitters have this same weakness, but are easier to install higher than the breeching tap to ensure they stay dry. Draft transmitters usually include filters to help reject boiler pulsation and transmit just the boiler draft. Once the draft signal is digitized, it is easier to manipulate in a digital controller.

–PID controllers have replaced proportional only controllers. Although the derivative component of the PID control is rarely used, the integral component helps the controller respond faster to quick load changes. Floating point, and gap PID controls utilize a lower proportional gain when the draft is close to setpoint to help eliminate controller oscillation during normal operating conditions.

–Firing rate is often used as a feed-forward input to the draft controller. During commissioning, the technician determines the best draft damper position at 20%, 40%, 60%, 80%, and 100% firing rates. During quick load changes the draft controller monitors the burner firing rate and quickly moves the stack damper to these predetermined positions. As the firing rate begins to level out, the PID controller takes over again to trim the damper position to hold the draft setpoint for that load.

–Modern draft controllers have an adjustable start position—a separate damper position or draft setpoint used only for burner lightoff. If the technician is fighting an unstable pilot, he can position the draft damper or draft setpoint where he needs it to ensure a stable pilot flame and reliable main burner lightoff.

–A digital draft controller can generate a high or low draft pressure alarm, a low draft pressure shutdown contact to the burner management system, and can communicate digitally to a plant-wide control system.

Although positive pressure boiler designs have reduced the need for draft controls, the sensitivity of low NOx burners has actually increased the use of draft controls in recent years. As burner performance standards for low excess air, low NOx operation have increased, the performance requirements for draft controllers have increased proportionately. As the inset article at the beginning of this post shows, Preferred Instruments was one of the earliest providers of boiler draft controls. Today, Preferred Instruments continues to manufacture the most advanced draft control products available to handle any draft control application.

The JC-22D stand-alone draft controller interfaces with most burner management system and combustion controller to safely monitor and control furnace draft in virtually any application.

The Preferred JC-22D

JC-22D 

The JC-22D stand-alone draft controller interfaces with virtually any burner management system and combustion controller to safely monitor and control furnace draft in virtually any application.”

 

BurnerMate Universal

The BurnerMate Universal boiler controller incorporates burner management, combustion control, feedwater control, and draft control for complete boiler control in one easy-to-use package. The BMU incorporates all the draft control functions of the JC-22D. Because it is integrated with the other boiler control functions, the only field device required is a draft transmitter and draft damper actuator.

The BurnerMate Universal

The BurnerMate Universal

 

When thousands of exhibitors and visitors descended on New York City for the 2014 AHR Expo, many of them weren’t prepared for the sudden snow storm that blanketed the streets of downtown Manhattan.  Preferred Utilities, however, came well prepared–and stirred quite a buzz by bringing several big items to the big apple.

Preferred Utilities debuted its new Advanced Performance Inject-Air Low NOx Axial Flow Burner (API-AF). This burner includes Preferred’s first packaged burner unit for 4MMBTUH-20MMBTUH applications.

API AF outside

API-AF Burner

By producing an exceptionally stable flame at all firing rates, the API-AF offers the same high efficiency, low emissions, fuel variety, and ease of maintenance of the original API burner–just in a smaller, more robust package.

API AF inside

API-AF Burner (open)

Included in the API-AF package is the new BurnerMate Light controller. Boasting UL approval, the BurnerMate Light provides an economical, state-of-the-art microcomputer-based burner management system with built-in first-out annunciatior and combustion control for a single burner, boiler, or process heat application.

BurnerMate Light

BurnerMate Light

Preferred Utilities also made a splash with its new Waterproof Pumps – an innovation spurred by Hurricane Sandy. The flooding in areas like New York and New Jersey emphasized the need to rethink mission critical infrastructure. Preferred developed the Waterproof Pump to operate uninterrupted during flood events, ensuring the safe supply of fuel for emergency generators and boilers.

WP Waterproof Pump

 

 

Also at the show: Preferred’s new Fuel System Controller (FSC). The FSC is Preferred Utilities’ next generation programmable logic controller with features specifically designed for critical data center and health care backup generator fueling systems.  FSC controllers automate fuel oil pump sets, suction integrity test, leak detection monitoring, generator day tank level control, day tank return pumps, main tank filtration/chemical treatment skids, multiple main tank motorized selector valves, tank gauge integration, tank truck off-loading , and much more. The FSC distributed control architecture avoids common mode failures. Each FSC has an independent power supply, CPU and I/O . Multiple FSC controllers communicate over a masterless, electrically  isolated, dual redundant network.

If you need to rethink your mission critical strategy–or if you would like further information on any of these new products–please contact Preferred today!

(203) 743-6741