Editor: Matt Keenan

715-648-5000

IMPORTANT

that everything you did was so automatic that you cannot remember stopping at the last intersection or not. You’re sure you did but cannot remember. This same thing oc-curs when I finished an inspection on the 5th boiler of the day. Did I remember to look for ventilation, combustion controls or did I do a complete walk around before signing off on the inspection. I’m sure I did but can-not remember.

Our inspections become so automatic that we should, not shall, commit to one whole day a week going through checklists for each type of pressure vessel. I am also committing to take a safe driving checklist with me to measure my performance once a week. When I first tried this approach I was surprised at how much I missed on the checklist. By doing this activity what I found most rewarding was that because I slowed down and checked everything off that one day, the rest of the week, without using the checklist, I performed more thorough in-spections and drove more attentively.

Please join me in the 2015 Challenge and commit to this endeavor. I am providing you the one page checklists I edited for pressure vessels we most encounter along with a Safe Driving Assessment checklist on our web site {thewbia.com} under the COOL DOCS tab on the Home page. On the Wisconsin Department of Safety and Professional Services website the check-lists are also available at:

http://dsps.wi.gov/Home [ Industry Ser-vices ] [ Safety and Building ] [ All Division Programs: Boilers ] [ Boilers, Pressure Vessels: Forms ]. I hope you make the commitment and if you have any questions or need a form you can always e-mail me at jay.eckholm@fmglobal.com

Hello everyone, I am excited about our 2015 Annual Industry Days Seminar next year at the Chula Vista Resort in Wisconsin Dells on the 15th and the 16th of April. You’ll find more specifics in this Newsletter and on our Website at thewbia.com.

Last year’s seminar, which combined Minnesota and Wisconsin inspectors, was our largest turnout. The Critique Sheets you filled out stated that you were very pleased and that the presentations were informative and the speakers did a great job sharing their experiences and knowledge. It would be great to see eve-ryone once again in 2015 and if you pass the word around we should be able to surpass our previous attendance.

Make sure you visit https://app.wi.gov/licensesearch to see if your Continuing Education Credits are current and you have enough of them to meet the criteria for renewal. You will find your data by opening the tab labeled [Trades Creden-tial/License Search] and typing in your credential ID. The 2015 Challenge: I am looking to raise my game in 2015 and want all in-spectors to join me in this challenge. Our commitment will be to use checklists to help us focus better while doing routine inspections. Our pledge would be to use these lists just once a week for every week in 2015. The reason why I am chal-lenging us this way is because while pro-cessing numerous inspections there are times that, if I were honest, I am just go-ing through the motions.

Sometimes we inspect like we drive. You may have felt this from time to time that after driving for miles you come to realize

A WORD FROM THE PRESIDENT

Volume 21, Issue 3

Fall 2014 Issue

The Chief’s Words!

By: Mike Verhagen

2

City of Milwaukee News

By: Jillian Klug

3

Combustion 101 4

Is Measuring Draft

Important

7

Minnesota & Wisconsin

Inspectors Maps

8

Main Items for Combus-tion Safety

10

Combustion Efficiency 12

Boiler Formulas 14

Modulating Boilers 16

Please visit our

Sponsors

6, 9

& 13

Inside this issue:

2015 11th Annual

Boiler Seminar

Wisconsin Dells April 15th & 16th, 2015

2 Days of Combustion Training

by CEC Combustion Safety

Volume 21, Issue 3 Page 2

The Chief’s Words: By: Mike Verhagen, Chief Boiler Inspector

I am ready for deer hunting this year and will hit the trail the third week in November in central Wisconsin. The weather forecast indicates it may be colder than usual but that will keep the beverages chilled. I will prepare some jerky this weekend so we won’t go hungry at camp. My Dad, three sons and I should be success-ful this year as my sure shot (2) youngest sons have been known to shoot two deer at a time. My Daughter has returned to India to continue “Yoga” for the winter (actually she dislikes the winter) and may come back in the spring or summer next year but we will miss her during the Holidays. Still have vacation days to sched-ule so I look forward to using them to celebrate both Thanksgiving and Christmas with family and friends. Best wishes to all for a safe, healthy and enjoyable Hol-iday season.

I am happy to report the WBIA committee members have secured a Seminar Training date for …. April 15-16, 2015 …. for our 11th ANNUAL” Boiler Safety Indus-try Days, so mark your calendar. In brief, the training location is at the Chula Vista, Wisconsin Dells, WI so our neighboring MN contractors - inspectors will not have to travel far to attend for the second year in a row. Get your travel plans ready and mark your calendar today to attend another “joint” Minnesota and Wiscon-sin Industry Days Seminar in 2015. Further details can be obtained from our website or from our fall /Spring Newsletter. CEC Combustion Safety will cover both days of training.

Note; MN Chief Joel Amato plans to buy an old school bus and pick up everyone west of the Mississippi for fun to, from and at the 2015 Industry Days Seminar.

If you haven’t tried the WBIA website @ www.thewbia.com time to do so is now and save it as a favorite. Sponsors help to keep the mouse working so pay them a visit too. Try it, and spread the word and tell others about our upcoming 2 day CEC Combustion Safety Seminar at ChulaVista Resort Wisconsin Dells, WI.

DEPARTMENT NEWS

The Department of Safety and Professional Services (DSPS) is moving Wisconsin forward. Retirements from state service has slowed and Brock McHenry comes onboard with initial orientation scheduled in the Madison office on November 17th. In addition to being Bureau Sec-tion Chief of the Elevator, Gas Systems, Boiler & pressure vessel, Mechanical Refrigeration and Structural Welding Programs, he will be wearing the hat of Waukesha office manager. The office staff will welcome him on the 18th.

For those who may have not heard Rick Merkle unexpect-edly retired from State Service a few short weeks after our last April’s 10th Annual Industry Days Training. We wish him well in retirement which is hoped to be filled with many opportunities in a long, happy and healthy retire-ment ahead.

Eat well during the Holidays and thanks again for your cooperation and support.

Think Family and friends as we begin looking forward to the Holidays!

Department Safety and Professional Services DSPS - Boiler Safety, Division of Industry Services

141 NW Barstow St, 4th Floor

Waukesha WI 53188-3789

Mike Verhagen, Chief Inspector

mike.verhagen@wi.gov

262-548-8617

DEPARTMENTAL CORRESPONDENCE

Continue to mail general correspondence to the Madison office:

DSPS -Industry Services/Inspection Support

PO Box 7302

Madison WI 53707-7302

INSPECTOR MATERIAL ORDERS

Material orders for registration tags “B or U” # s, may be ordered via materialorders@wisconsin.gov

(Con’t page 3)

City of Milwaukee Department News:

By: Jillian Klug, Chief, City of Milwaukee

Greetings from the City of Milwau-kee. A lot has transpired since the last WBIA newsletter. Most notably, Paul Wilcox, former City of Milwaukee Chief Boiler Inspec-tor, hosted a highly attended re-tirement party in May and we all wish him the best in his retire-ment. A few months after Paul’s well deserved retirement the city of Milwaukee hired Adrian Gibbs as a new Boiler Inspector. Mr. Gibbs is currently work-ing towards earning his National Board Inservice Commission. Presently our Boiler and Mechanical Safety Section inspection team consists of Mr. Gibbs, the knock-out inspector Jim Smith, and me. I have been appointed as the new City of Milwaukee Chief Boiler Inspector and I look forward to serving the City of Milwaukee in my new role. As always, we are working to keep up with the re-quired periodic boiler and pressure vessel inspections. I’d like to encourage all inspectors to communicate to me when an object in the City of Milwaukee has been inspected but has areas to correct before the Permit to Operate can be issued. This communication will assist us in avoiding the issuance of overdue fines against a customer who has met their obligation and has had their boiler or pressure vessel inspected. I look forward to seeing everyone at the annual Boiler Industry Days in Wisconsin Dells, April 15th and 16th, 2015. Jillian C Klug Chief Boiler Inspector, City of Milwaukee City of Milwaukee Boiler and Mechanical Safety Section Department of Neighborhood Services 841 N Broadway, 10th Floor Milwaukee, WI 53202-3613 Email:

jklug@milwaukee.gov Office: (414) 286-2536 Fax: (414) 286-3939 http://city.milwaukee.gov/Boiler

Volume 21, Issue 3 Page 3

Wisconsin Chief Words (con’t from page 2)

WEB SITE INFO

Wisconsin Boiler inspector’s Association

www.thewbia.org Coming soon … 2015 Industry Days Details

National Board

www.nationalboard.org

ASME

www.asme.org

DSPS …Industry Services, then Boiler Program

http://dsps.wi.gov/Programs/Industry-Services/Industry-Services-Programs/Boilers-and-Pressure-Vessels//Programs/Industry-Services/Industry-Services-Programs/Boilers-and-Pressure-Vessels/

Credential–License Check …verify current certifications, registrations & licenses

https://app.wi.gov/licensesearch

City of NY Fire Engine

On the evening of June 18, Fire Engine Company No. 9 from East Broadway was called to a fire opposite the Bow-ery Theatre. The fire was put out without difficulty, but just as theater crowds went into the street during intermission, the boiler of this steam engine exploded, hurling scalding water and metal fragments into the air over a wide area. The disaster left five dead and 22 injured.

Volume 21, Issue 3 Page 4

So what is happening at that burner? There is a lot more to a burner than just some fire being blown into a boiler or other heating device. Just what is a burner supposed to do? 1. Provide heat to the boiler. 2. Control the outlet temperature or pressure of the boiler

or heating device. 3. Provide a means for turndown so that the burner does

not shut off over the full range of the boiler or heating device.

4. Burn the fuel in the most efficient way possible. There are a couple of terms that we should know . Excess Air: The extra amount of air added to the burner above that which is required to completely burn the fuel Turndown: The ratio of the burner’s maximum BTUH firing capability to the burner’s minimum BTUH firing capability There are some basics when it comes to burner functions. Natural gas and fuel oils follow the same basic rules. When a fuel such as natural gas or fuel oil is mixed with the prop-er amount of air and heated to the combustion tempera-ture, it burns. The below shows the process with the amount of air and fuel required for perfect com-bustion of natural gas.

What people forget is that those fans supplying air for com-bustion moves a constant volume of air, not molecules.

Any change in temperature or barometric pressure causes a change in the number of air molecules that the fan moves.

Combustion 101

Those valves that control the fuel and the pressure regulators are not perfect devices either so the gas flow cannot be a perfectly constant. The gas train is designed to control volume much like the air system, so a change in gas temperature will also change the number of molecules burned.

To ensure safe operation at all temperatures of air and fuel and at all barometric conditions, the gas burner requires that excess air supply.

So the good news is that excess air does provide a measure of safety. The not so good news is it wastes fuel. Excess air is a waste of fuel!

The boiler is merely a heat exchanger device de-signed to absorb the heat of combustion products and to transfer that heat into water. When excess air is added to the perfect (stoichiometric) amount of air, obviously more mass is forced through the boiler. In a boiler, there is a modulating control that meters air and fuel so that the proper amount of heat is added to maintain the proper pressure and temperature. Because of this control, the same amount of BTU’s are absorbed per hour, no matter what the excess air amount supplied is. As mass flow is increased in this heat exchanger the outlet temperature is increased. The mass amount is analogous to the amount of excess air used by a burner.

In a boiler, as the excess air is increased, the stack temperature rises and the boiler efficiency drops. It takes fewer BTU’s of input to the burner to get the same number of BTU’s out of the boiler if lower ex-cess air can be used. So one of the most important functions of a burner is to burn the fuel at the lowest possible excess air to achieve the greatest overall boiler efficiency.

(con’t page 5)

Volume 21, Issue 3 Page 5

Combustion 101 (Con’t from page 4)

There are strong reasons why high turndown and low excess air are important. The first of course is the oper-ating cost of the burner. We shown how excess air can affect the operating cost, but the turndown ratio of a burner also has a big affect on cost. Every time the burner starts and stops there is a cost associated. Air is always blown through the boiler to assure that there is no unburned fuel remaining. These purges make the boiler work like a chiller because it takes energy out of the system. Two other reasons for having a high turn-down relate to lowered maintenance cost and better pro-cess or heating control. Please don’t confuse turndown to “fully modulating” burn-ers. Having a fully modulating burner with only the typi-cal turndown of 1.7 to 1, is liking having a car that can only go between speeds of 59mph and 100mph. It is a ”fully modulating” car all right but try driving it to the gro-cery store! You’d not only look silly, but think of how the gas mileage would drop! The chart shows how turn-down ratio of a burner impacts the fuel cost needed to run a 100 horse-power boiler for heating.

The figures below are simplified burner heads. Air is brought into the head by means of a forced draft blower or fan. The gas is metered into the head through a

series of valves. In order to get proper combustion, the air molecules must be thoroughly mixed with the gas mol-ecules before they can actually burn.

The mixing is achieved by burner parts designed to cre-ate high turbulence. If insufficient turbulence is produced by the burner, the combustion will be incomplete and samples taken at the stack will reveal carbon monoxide as evidence.

Since the velocity of air affects the turbulence, it be-comes harder and harder to get good fuel and air mix-ing at higher turndown ratios since the air amount is re-duced. Towards the highest turndown ratios of any burner, it becomes necessary to increase the excess air amounts to obtain enough turbulence to get proper mix-ing. The better burner designs will be the ones that are able to properly mix the air and furl at the lowest possi-ble air flow or excess air.

The chart shows the savings realized with a 100 horse-power load at various efficiencies caused by different excess air levels.

Volume 20, Issue 1

Page 6

Volume 21, Issue 3 Page 7

Thought of the Day Be not inhospitable to strangers, lest

they be angels in disguise

When you combine the effects of low excess air and high turndown, the operating cost savings can range from 10% to 15% below a burner that does not have those characteristics. Process control is enhanced with a high turndown. If the load is smaller than the burner can turn down to, it cycles on and off. When off, the pressure or temperature falls off. On some boilers, you can see steam pressures drop from 100psig at burner shutdown to about 40psig before the burner comes on again. That can cause problems in a manufac-turing plant that depends on a constant steam pressure. Even on a hot water heating systems, control problems occur because of low turndown boilers. Valves can hunt and temperature control can be-come erratic. With high turndown, those fluctua-tions are elimi-nated be-cause the burner tracks the load down to a point where it shuts off only when the load is very slight. There is enough stored energy in the system to take up the small fluctuations at that point. Maintenance costs are usually reduced with a high turndown burner because there is less thermal cy-cling taking place in the boiler. When a burner cy-cles, the refractory and metal parts expand and contract. Although those materials are built to take it, their life is prolonged if everything stays the same temperature. Gas valves, ignition transform-ers, etc. are all less likely to fail if they never cycle.

Combustion 101 (Con’t from page 5)

Is Measuring DRAFT Important?

The pressure of the gases in the stack must be carefully controlled to insure that all the gases of combustion are removed from the combustion zone at the correct rate. This draft pressure can be positive or negative depending on the boiler design; Natural draft, Balance draft, and Forced draft boilers are the most commonly used in the industry.

Monitoring draft is important not only to increase com-bus-tion efficiency, but also to maintain SAFE conditions. Low draft pressures create build-ups of highly toxic gases such as carbon monoxide and highly explosive gases. These build ups may take place in the combustion chamber or may even be ventilated indoors creating the risk of injury and death. Conversely, extremely high draft pressures can cause unwanted turbulences in the system preventing complete combustion. Unwanted high draft pressures tend to damage the combustion chamber and heat exchanger material by causing flame impingement.

The following operating difficulties can result from un-controlled draft: Poor Combustion Efficiency Pilot/Main Flame fails to light or is unstable, causing

shutdowns Soot accumulations due to varying fuel oil ratios

Volume 21, Issue 3 Page 8

Wisconsin Inspectors Map

IMPORTANT

Continuing Education Requirements for All National Board Commissioned Inspectors Started in 2005!

Attending the WBIA Seminars helps you meet the Wisconsin training re-quirements.

Minnesota Inspectors Map

Inspector Territory Phone number Email address

Joel Amato Chief (651) 284-5137 joel.amato@state.mn.us

Rock Anderson Northeast (218) 940-9202 rock.w.anderson@state.mn.us

John Purdy North metro (651) 216-9013 john.purdy@state.mn.us

Tom Boyle Southeast metro (651) 303-2764 tom.boyle@state.mn.us

Keith Dauer Metro and south central

(507) 381-5021 keith.dauer@state.mn.us

Vacant North metro 2

Jeff Formo West central (218) 206-3905 jeffrey.formo@state.mn.us

Rebecca Hayes Northwest (218) 239-0138 rebecca.hayes@state.mn.us

Jim Neumann Southwest (651) 247-3962 james.neumann@state.mn.us

Jeff Rendler Southeast (651) 295-8374 jeff.rendler@state.mn.us

David Gonsoski East metro (651) 247-3857 david.gonsoski@state.mn.us

Volume 20, Issue 1 Page 9

Main Items for Combustion Safety Item Safety Reason

Air Purge (startup) Before lighting the boiler burner, the air blower is operated long enough to dis-place 4 times the boiler combustion chamber volume.

If natural gas and air are inside the boiler when the burner is lit, the boiler can explode.

High Natural Gas Pressure A pressure switch in the natural gas line stops the burner if the gas pressure gets too high.

If the natural gas pressure control valve fails, excessive gas can flow to the burner. If too much natural gas flows to a com-bustor, the burner could go out or the flame could be large enough to cause overheating. If the flame goes out and natural gas continues to flow, a combustible mixture could fill the boiler combustion chamber (explosion hazard).

Low Natural Gas Pressure A pressure switch in the natural gas line stops the burner if the gas pressure gets too low.

If the natural gas pressure falls too low, the burner could go out. If natural gas is still flowing, a combustible mixture could fill the boiler combustion chamber (explosion hazard).

Low Flame Strength A flame detector stops the burner if the flame becomes weak or goes out.

If the flame goes out, natural gas flowing through the burner could cause an explosive mixture to fill the boiler combustion chamber (explosion hazard).

Air Blower Not Running A switch stops the burner if the air blow-er is not running.

If the air blower is not running, the burner cannot operate.

Low Combustion Air Flow A pressure switch in the burner air ple-num stops the burner if air pressure gets to low (meaning the air flow is too low).

If the air flow becomes low, the flame may become weak or go out even though natural gas is still flowing (explosion hazard).

High Steam Pressure A pressure switch in the steam chamber stops the burner if the pressure gets too high.

If the burner continues firing even when steam flow is low, the boiler pressure can build and the vessel can explode.

Low Water Level A level switch stops the burner if the boiler water level gets too low.

If the water levels gets low enough that part of the boiler runs dry, that part can overheat, weakening it and possibly resulting in an explosion.

Natural Gas Pressure Regulator An automatic pressure regulating valve steps natural gas supply pressure down to the level needed by the burner.

If the natural gas supply line pressure rises too much, the burner may over fire, putting out the flame or overheating the boiler.

Natural Gas Drip Leg A drip leg (low point drain) located near the Natural Gas Pressure Regulator traps debris in the natural gas supply.

If solid or liquid debris enters the natural gas supply valve train, operation can be affected.

Natural Gas Block & Vent Valves Two automatic block valves with a vent valve between them are used to stop natural gas from reaching the burner when it is off. The block valves have position switches so the control system knows when they are close.

A single automatic block valve in good condition would be enough to stop natural gas flow, but a second automatic block valve provides insurance. A vent valve between the block valves pipes any leakage gas to atmosphere when the block valves are closed.

Linked Natural Gas and Combustion Air Valves

The flow control valves for natural gas and combustion air are linked mechani-cally – as one is opened or closed, the other does the same.

If too much or too little combustion air is supplied with the natu-ral gas, the flame can go out.

"Self-Checking" Flame Detector The flame detector has a mechanical shutter which blocks the detector tubes view of the flame periodically. If the detector tube still sees flame when blocked, the detector has failed and the burner shuts off.

If a flame detector tube fails it must be replaced. Sometimes these tubes can fail in the "flame OK" position – if this happens the burner could go out and the detector would not know. NFPA guidelines require self-checking detectors when the burner operates more than 24 hours without shutdown.

Volume 21, Issue 3 Page 10

Main Items for Combustion Safety

Con’t from page 10

Item Safety Reason

Boiler Steam Pressure Emergency Relief Valves

Two special relief valves vent steam from the boiler if the pressure reaches dangerous levels.

If the pressure controller and the high pressure switch shut-down circuit fail, these valves prevent excessive steam pres-sure from destroying the boiler.

Water Level Gauge Glass A special gauge lets the operator view the boiler water level directly.

If the level control instruments malfunction, the operator can still monitor water level and take appropriate action.

Low Fire To Light the Main Flame The control system drives the burner main natural gas control valve to "low" flow when the main flame is to be light-ed.

The pilot flame is much smaller than the main flame and may be unable to light the main flame if fuel gas is flowing at maxi-mum rate.

Interrupted Pilot Burner The small pilot burner turns off as soon as the main burner is lit.

A single flame detector is used in this system. It must be locat-ed to see both the small pilot flame and the large main flame. If the pilot operates all the time, and a problem with the main flame caused it to go out, the system would not detect the flame loss. At high burner firing rates, the pilot flame may be too small to reignite the main flame.

Notes: With a separate flame detector for both the main flame and the pilot flame, the pilot can remain on all the time. Also, with a large pilot flame (usually at least 10% of the main flame) re-ignition of the main flame is very likely and the pilot can remain on even with a single flame detector in use.

Volume 21, Issue 3 Page 11

When assessing your site’s level of combustion equipment risk, remember the following:

Most of the explosions and fire incidents, by far, have been due to human error. All of the safeties and interlock equip-ment in the world won’t help if someone has bypassed or jumpered-out safety controls. There is no possible substitute for proper training. Training has to include mock upset and hazard recognition drills. Your people need training even if you will have contractors heavily involved at your site.

Start-up and shutdown are your biggest risks. You need clearly written procedures that everyone understands and agrees with so that consistent safe practices are in place with every shift and every employee.

Make sure you do regular and complete interlock and fuel train valve tightness testing. Jurisdictional inspectors, even where they are mandated to be around, cannot be at your facility every day. Combustion equipment safety testing needs to be part of your organization’s culture regardless of what it costs and what the perceived hurdles are. You should comply with code requirements for testing even if some inspector is not forcing you to.

Create corporate guidelines for third party combustion equipment reviews and commissioning for newly acquired equipment or for major upgrades. Now that you see how little review and attention combustion equipment may receive from the time it’s specified to when its really operating, you may want a dedicated professional review of the design and what you are getting by a qualified experienced third party.

Upgrade equipment for safety’s sake. There’s no peace of mind in being grandfathered. Do not wait for a problem and let attorneys dictate upgrades that need to happen because of a lawsuit. Do a gap analysis proactively and have a long-term plan to be compliant with the most recent codes.

The above was written in a National Board article “Top Ten Boiler and Combustion Safety Issues to Avoid.”

Volume 21, Issue 3 Page 12

Two of the most important operating factors entering into the consideration of what constitutes a satisfactory boiler are its efficiency and capacity.

Total efficiency is defined as the effectiveness of any combustion apparatus to convert the internal energy contained in the fuel into heat energy for use by the process.

Below is how the ASME looks at efficiency. Boiler effi-ciency may be indicated by:

Combustion Efficiency—Indicates a burners ability to burn fuel measured by unburned fuel and excess air in the exhaust.

Thermal Efficiency—Indicates the heat exchangers effectiveness to transfer heat from the combustion pro-cess to the water or steam in the boiler, exclusively radiation and convection losses.

Fuel to Fluid Efficiency—Indicates the overall efficien-cy of the boiler inclusive thermal efficiency of the ex-changer, radiation and correction losses output divided by input

Stoichiometric or Theoretical Combustion is the ideal com-bustion process where fuel is burned completely.

A complete combustion is a process burning all the carbon (C) to (CO2), all the hydrogen (H) to (H2O) and all the sul-phur (S) to (SO2).

With unburned components in the exhaust gas, such as C, H2, CO, the combustion process is uncompleted and not stoichiometric .

The combustion process can be expressed as:

[C + H (fuel)] + [O2 + N2 (Air)] -> (Combustion Process) -> [CO2 + H2O + N2 (Heat)]

Where:

C = Carbon

H = Hydrogen

O = Oxygen

N = Nitrogen

To determine the excess air or excess fuel for a combus-tion system we start with the stoichiometric air-fuel ratio. The stoichiometric ratio is the perfect ideal fuel ratio where the chemical mixing proportion is correct. When burned all fuel and air is consumed without any excess left over.

Process heating equipment are rarely run that way. "On-ratio" combustion used in boilers and high temperature pro-cess furnaces usually incorporates a modest amount of excess air about 10 to 20% more than what is needed to burn the fuel completely.

If an insufficient amount of air is supplied to the burner, un-burned fuel, soot, smoke, and carbon monoxide exhausts from the boiler resulting in heat transfer surface fouling, pollution, lower combustion efficiency, flame instability and a potential for explosion.

To avoid inefficient and unsafe conditions boilers normally operate at an excess air level. This excess air level also provides protection from insufficient oxygen conditions caused by variations in fuel composition and "operating slops"

Example - Stoichiometric Combustion of Methane - CH4

The most common oxidizer is air. The chemical equation for stoichiometric combustion of methane - CH4 with air can be expressed as:

CH4 + 2(O2 + 3.76 N2) -> CO2 + 2 H2O + 7.52 N2

Continued on page 14

Combustion Efficiency

Volume 21, Issue 3 Page 13

WISCONSIN MINNESOTA

3301 E. Evergreen Dr. 6291 318th St Appleton, WI 54913 Cannon Falls, MN 55009 Telephone: 920.832. 9778 Telephone: 507.263.2251 Fax: 920.832.9798 Fax:866.929.3719

Contact Us:

http://www.alliedvalveinc.com/index-5.html

Volume 21, Issue 3 Page 14

Boiler Formulas Combustion Efficiency Con’t from page 12

If more air is supplied some of the air will not be involved in the reaction. The additional air is termed excess air, but the term theoretical air may also be used. 200% theoretical air is 100% excess air.

The chemical equation for methane burned with 25% excess air can be expressed as

CH4 + 1.25 x 2(O2 + 3.76 N2) -> CO2 + 2 H2O + 0.5 O2 + 9.4 N2

Excess Air and O2 and CO2 in Flue Gas .

Approximate values for CO2 and O2 in the flue gas as result of excess air are estimated in the table below:

In the actual combustion processes, other products

are often formed. A typical example of an actual combustion process is shown below. Fuel has re-acted with air to produce the products found on the right.

The combining of oxygen in the air and carbon in the fuel to form carbon dioxide and generate heat is a complex process, requiring the right mixing turbu-lence, sufficient activation temperature and enough time for the reactants to come into contact and combine. Unless combustion is properly controlled, high concentrations of undesirable products can form. Carbon monoxide (CO) and soot, for exam-ple, results from poor fuel and air mixture or too little air. Other undesirable products, such as nitro-gen oxides (NO, NO2 ) form in excessive amounts when the burner flame temperature is too high. If a fuel contains sulfur, sulfur dioxide (SO2) gas is formed. For solid fuels such as coal and wood, ash forms from incombustible materials in fuel.

The American Society of Power Engineers, Inc. (ASOPE®) is an independent third party licensing agency whose objective is to establish national standards and a formal structured level of competence for na-tional and international recognition of the power engineer.

ASOPE® is not a labor organization and is not affiliated with any other organizations. ASOPE® recogniz-es and promotes other organizations such as the American Society of Mechanical Engineers, National Association Power Engineers, National Board of Boiler and Pressure Vessel Inspectors, and governmen-tal regulatory agencies such as Environmental Protection Agency and OSHA.

ASOPE Region 2 Email reg2@asope.org Area Covered: Wisconsin, Illinois, Upper Michigan, Iowa, Minnesota and Missouri

Power Engineer Competency License Program

The American Society of Engineers has three license program categories. The first is the Main Power Engineer Competency license program, the second is the Supplementary Power Engineer Competency license program and the last is The Hobbyist and Specialty Power Engineer Competency license program.

Volume 21, Issue 3 Page 16

There are 3 basic types of modulating burner con-trol:

Fully Electronic:

This will independently control the fuel and air vol-ume to the burner via separate fuel and air valves, normally this type of control will have an integral proportional-integral-derivative controller (PID) load control to ensure that the boiler's set point is being maintained to the boiler's load requirements. This type of system offers high levels of combustion con-trol and consistency.

Fully Mechanical:

This controls the non linear relationship between the fuel and air ratios, a characterization cam is used (sometimes call a compound control). This is linked directly to the fuel valve and air damper of the burn-er; this has a limited control resolution due to the hys-teresis and lost motion of mechanical systems i.e. inertia, friction, wear and tear.

Fully Pneumatic:

This type of system is very commonly used by burn-er manufacturers as a low cost solution for gas fired burners only. The burner has a gas control valve that is operated by a diaphragm and impulse line from the burner's air supply to the burner.

The burner will have a PID load control that directly controls the burner air damper to give the required air volume, the gas valve will operate to give a di-rectly proportional gas volume according to the cor-rect fuel/air ratio.

With this type of system, it is limited to the air con-trol of the burner and suffers from hysteresis and limited turn down ratio.

Modulating burners are designed to constantly match the firing rate according to the boiler load de-mands and in a perfect case, the burner would re-main firing constantly whilst heat is required. This however, is rarely achieved for the following rea-sons:

Limited Turn Down Ratio:

The "turn down ratio" is a function of the burner's ca-pacity to match the current base load of the boiler i.e.

a 400kW boiler may have a burner that is correctly sized for the boiler application, for example the burner at high fire will give a output of 400 kW (100%) and at low fire will give an output of 100 kW (25%) this would be re-ferred to a "turn down ratio" of 4:1.

If the above example is used and that the base load re-mains at above 100 kW the burner will modulate without turning off and "dry cycling " will not occur. However, if the base load is below 100 kW the burner will reach and exceed the set point and the burner will turn off and "dry cycle".

Other factors that will cause the burner not to modu-late:

The boiler manufacturers do not normally manufacture the burner to be fitted to the boiler; this is left to the appli-cation and the customer's requirements to remain flexi-ble and not to limit the boiler market. In this case the specified burner and type of burner will be deemed suita-ble.

The burner manufacturers offer a range of burner types and capacities, in most cases the burners output is not perfectly matched to the boiler output and as a conse-quence the burner is not able to fire below the minimal base load. This will in most cases cause the burner/boiler to cycle on and off, wasting energy.

Modulating burners with poor "turn down ratios" i.e. 2:1 will act as a high/low or on/off burner again causing excessive boiler cycling, wasting energy.

Incorrectly sized boilers for their applications will also cause modulating burner to operate as on/off burn-ers.

Incorrectly commissioned modulating burners with poor combustion and, or incorrectly commissioned PID load controller, will also cause the burner not to modulate.

Summary:

Modulating burners rarely operate as designed due to the above, further with the intervention of BMS control, the boiler will turn off before the burner has had time to fully modulate to low flame conditions or indeed at high fire. Historically 97% of modulating burners do not have sufficient turn down or control to give constant burner operation and cause boilers to dry cycle, and therefore waste energy.

Modulating Burners

APRIL 15th & 16th, 2015

Chula Vista Resort 2501 River Road,

Wisconsin Dells, Wisconsin 54650

For Hotel Reservations for the WBIA

call - 855-666-8207

Great training is planned. CEU’s each day will be awarded for everyone in attend-ance. A Certificate of Attendance will also be issued at the end of the event. For more information and to Sign up go to the WBIA Website to Register. thew-bia.com. PayPal is available. Rooms Will Be Going Fast!

Agenda items may not be given in order listed. CEU’s will be awarded per day.

A special room rate has been assigned for those needing lodging during this seminar. Please contact the hotel and inform them you are attending the WBIA Industry Days Seminar.

Ask for WBIA Conference Rate of $70/single The hotel does accept State Rates. Reservations should be made by April 1st after which rooms are not guaranteed

Agenda….April 15, 2015, Wednesday 0700-0800 Sign In (Registration) 0800-0900 Wisconsin Chief’s Welcome 0900-0915 Break 0930-1030 Minnesota Chief’s Welcome 1030-1045 Break 1045-1200 Combustion 1200-1300 Lunch 1300-1430 Combustion, con’t 1430-1445 Break 1445-1630 Combustion, con’t

Agenda….April 16, 2015 Thursday 0700-0800 Sign In (Registration) 0800-0930 Combustion, con’t 0930-0945 Break 0945-1145 Combustion, con’t 1145-1245 Lunch 1245-1430 Combustion, con’t 1430-1445 Break 1445-1600 Combustion, con’t

The WBIA is again glad to announce the upcoming 2015 Boiler Industry Days! A new year brings another challenge to each person to meet their continuing education requirements and the challenge to better oneself. Over the years we have heard your requests for combustion training. We are glad to present two (2) days of combustion training. We have contracted with CEC Combustion Safety of Cleveland Ohio to bring to you this two (2) training seminar. Our training will be at the Chula Vista Resort, 2501 River Road, Wisconsin Dells, WI 53965. The training is geared toward your industry personnel and boiler inspectors who have direct responsibility for operating and inspecting boiler combustion systems on a daily basis. Continuing Education Credits (CEUs) will be awarded from CEC and Kent State University College of Technology. The training will be led by an experienced combustion system instructor. An electronic copy of the training will be provided at the end of the sessions. Of course the WBIA will provide an excel-lent lunch and refreshment each day. Also the Chief Inspectors of Wisconsin, Milwaukee and Minnesota along with the State Inspectors from each State and City will be in house for you to meet and speak with. So please check the WBIA website @ http://www.thewbia.com/WP/2015-annual-industry-days/ to get sign up information and again we will have a PayPal connection for easy registration. Certificates of attendance will also be handed out at the end of each day. Looking forward to seeing everyone in April of 2015.

2015 Boiler Industry Days