boilers: basic operations and new technologies

Boilers: Basic Operations and New Technologies

DOUG RITCHIE, SELLERS MANUFACTURING COMPANY, ON BEHALF OFTHE AMERICAN BOILER MANUFACTURERS ASSOCIATION OC T. 27 , 2016

@2016 TRSA - 1800 DIAGONAL ROAD, SUITE 200, ALEXANDRIA, VA 22314 – 877.770.9274 - TRSA.ORG

Do I really have to use a boiler formy steam and hot water?


Can a guy representing theABMAreally tell me the real story?


Yes. Like the performance advances of the very practical and efficient internal combustion engine, today’s boilers provide thepractical, reliable and cost-effective steamand hot water to meet your operational needs.


Your source of steam and hot water is reliable and safe if properly maintained, inspected and operated, as with the automobile.


Your boiler or water heater is a pressure vessel with combustion equipment. It is designed with a variety of controls that will shut the unit down for your safety.


Independent Testing is YourAssurance

Underwriters Laboratories (UL) , Edison Testing Laboratories (ETL) and other testing agencyapprovals are examples of independent verification for acceptable products offered by boiler manufacturers.


Many Boiler Types

Boilers are manufactured in many different sizes and configurations depending on the characteristics of the fuel, the specified heat output and the required emissions. Some boilers are designed to produce hot water, while others are designed to produce steam.


Many Boiler Types

The basic pressure vessel with burner

works very well, while we pursue multiple

methods of creating and transferring heat

to the contents of the vessel.


Many Fuel Types


Boilers run on electricity, natural gas, propane, bio-gas from multiple sources, refuse materials, oil, coal, wood, hydrogen, solar and nuclear energy.

Many Fuel Types

Natural gas is emerging as an ideal packageof cost-effective, reliable, widely-availableand reduced-emissions fuel.

It is also significant that the USA has become the largest natural gas producer in the world.


Basic Classes of Boilers by Design Concept


Most boilers are classified as either“firetube” or “watertube”.

Firetube Design Class

The “fire” is in the tube(s) and the water is outside the tube(s).


Watertube Design Class

The water is in the tube(s) and the “fire” is outside the tube(s).


Other Designs and Basic Principle


Designs such as cast-iron, coil-type andtubeless shell-type boilers are also available.

The intent is the same. Transfer as much heat content as possible from the fuel to the water for hot water or steam production.

Typical Boiler Metrics

Boilers are generally measured in BTU/hr. and Bhp output. (1 Bhp = 33,479 BTU or about 9.81KW/hr.)

Boiler efficiency can be measured by “stack” temperature, ultimately reflecting the amount of heat transfer from the fuel to the steam or hot water.


Typical Boiler Metrics


Boiler efficiency is also measured by fuel-to-steam efficiency, basically BTU input versus BTU output, also ultimatelyreflecting the amount of heat transfer from the fuel to the steam or hot water.

(But itdoesn’t consider cycling and purge losses, along with other operating

variables by application that will reduce actualefficiency.)

2 Major Types of Boilers byApplication

“Heating Boilers” and “Power Boilers” as determined by the American Society of Mechanical Engineers (ASME)


Heating Boilers

ASME states these are for “Steam heating, hot water heating, hot water supply boilers, and potable water heaters intended for low pressure service that are directly fired by oil, gas, electricity, coal or other solid or liquid fuels.”


Heating Boilers


Heating boilers that produce hot water are allowed to operate to 160psi or 250 deg F at or near the boiler outlet. If they produce steam, only to 15psi.

This type is identified with an “H Stamp”. (More on this marking shortly.)

Power Boilers

ASME states “Power, electric, and miniature boilers; high temperature water boilers, heat recovery steam generators, and certain fired pressure vessels.”


Power Boilers

Power boilers operate above 15psi for steam and above 160psi or 250 deg F for hot water.

This type is identified with an “S Stamp”.(More on this marking shortly.)


All pressure vessels fall under your “jurisdiction having authority”. Such authorities typically use the AmericanSociety of Mechanical Engineers Boilerand Pressure Vessel Code.


Another key player is the NationalBoard, made up of representativemembers from all US states. Thisorganization provides training and certification for inspectors working in state or municipal agencies, as well as insurance companies.


Per ASME, every pressure vessel manufactured must display a permanent stamp with 1) unique vessel identifiernumber and 2) unique Manufacturer’svessel number.


Each vessel manufactured is electronically and permanently recorded with the National Board, with details includingdestination location, prior to completion and shipment . The vessel is completely traceable from raw materials, through its manufacturing, to the client.


After shipment, it is up to the owner to conform to the requirements of the jurisdiction having authority where the boiler will be used.


Typical Boiler Permanent Stamps

Large Industrial Steam Boiler Small Commercial Water Heater

ASME H

Stamp


Inspection, Prevention, Good Operation


Your jurisdiction having authority typically follows ASME Section VII, for inspection of power boilers and SectionVI for heating boilers:

General Requirements for In-Service Inspection of Pressure-Retaining Items

Inspection is Mandatory


In general, if your unit is high pressure steam above15 psi, inspection is typically required annually.

In general, if your unit is hot water, inspectionis typically required every 3 years.

Your jurisdiction having authority will determinethe frequency of inspection.


Inspection is Mandatory – Frequency Inspection is Mandatory

The “pre-inspection activities” and “preparation for internal inspection” are usually carried out bycertified boiler mechanical contractors.

Larger operations have in-housecapability.

The inspector inspects, the owner does everythingelse.


The actual inspection activity is performed by yourlocal authority having jurisdiction or your insurancecompany.



There is no substitute for visual inspection both internally and externally, even though there mightbe good preventative maintenance.



Remember, your “jurisdiction having authority” has the final say on your overall boiler inspection, includingthe scope of the inspection, when it will be performed, code(s) compliance, inspection approval or denial with corrective action(s) and frequency of inspection.



Contact your local jurisdiction for yourarea’sspecific requirements.

You can get a state-by-state synopsisatwww.nationalboard.org



http://www.nationalboard.org/PrintAllSynopsis.aspx?Jurisdiction=Select

http://www.nationalboard.org/

http://www.nationalboard.org/PrintAllSynopsis.aspx?Jurisdiction=Select

Is your operation on a Periodic Inspection and

Preventative Maintenance program?


1. Overpressure

2. Weakening of the structure

3. Errors in operation of the combustionequipment

Per ASME, there are 3 general areas of

boiler/heater failure


Prevention - Overpressure

1. Steam pressure gages – readings, calibration

2. Pressure relief valves and fusible plugs,the last resort- leakage, damage

3. Water sight glasses – visual, level fluctuation

4. High and Low water level alarms, trips - indications


Prevention – Weakening of Structure

1. Boiler start-up - follow procedure to prevent stresson multiple-pass types, less an issue with single-pass and coil tube types (thermalgradients)

2. Control of water level – consistentsupply

3. Internal corrosion – maintain water quality (O2pitting)

4. External corrosion – maintain your room or shelter


Prevention – Weakening of Structure

5. Boiler shutdown – follow procedure to preventstress, again on the common multi-pass types

6. Boiler out of service – extended periodsprocedure

7. Failure of supports – joints, piping, foundation

8. Mechanical damage – blowdown, scale removal


Prevention – Operation of Combustion Equipment

1. Follow Manufacturer’s operating instructions in accordance withASME CSD-1 and NFPA85 standards

2. Only properly trained operators, familiar withfuel-burning equipment, should be in charge of theunits

3. Only qualified personnel should solve what appearsto be a malfunction, but is typically a proper safety shutdown. (It shutdown for a reason.)


1. Water leaks can be from loose connections, wornor defective components external to theboiler/heater

2. Unusual noises can be from air infiltration inthesystem, low water pressure or scaledeposits


Prevention – Symptoms “Hints and Tips” Prevention – Symptoms “Hints and Tips”

3. Pressure loss may indicate system steam leakage, defective pressure limit controls, return system check valve, steam trap, feedpump

4. Frequent cycling or shutdown can be result of room or air handler air intake restriction, stack/flue draft change, gas pressure drop, water level fluctuation,a change in demand during the day or from pastusage


TheASME has recommended rules for the care andoperation of boilers and related pressure vesseldevices

Good Operation


1. Water chemical and deaeration treatment for steam equipment, to maintain efficiency, reduce energy consumption, minimize maintenance, extend equipment life considerably (pH >8.5 and no oxygen greatly reduces corrosion)


Good Operation – “Some tips from the trenches”

2. Frequent blowdown water removal for steam equipment to remove accumulation of solids released from the water when turned to steam, that can otherwise lead to excessive scaledeposits and poor performance (manual or automatic)


Good Operation – “Some tips from the trenches” Good Operation – “Some tips from the trenches”

3. Good housekeeping –please keep the boiler room clean and clear of debris and “temporary” storage. Where does the air come into the room? Is it filtered? Is the room dry?


4. Hire a reputable mechanical contractor with aboilerspecialty or equivalent experience.

5. Consult with manufacturer’s representative to help train your personnel to properly maintain your equipment.



6. Please follow the manufacturer’s maintenance schedule, with alternative of schedules fromthe ASME, UL and in some cases your jurisdiction having authority.



New Technologies

1. Digital Modulating Immersion-Fired Single-Pass Steam or

Hot Water Firetube Boiler - provides volume rapid-

response cold water to steam in <20 minutes and

digitally modulates to your load demands


The TYPICAL MULTI-PASSFIRETUBE BOILER IS ALWAYS UNDER STRESS

Large

Temperature

Differentials

One Large

Diffusion

Burner Flame

into Large

Furnace Tube


The Immersion-Fired Single-Pass BoilerHeats Evenly and is Not Stressed

Individual

Pre-Mixed

High Velocity

Flames

Directly

into One

Tube Row


New Technologies

Digital Modulating Immersion-Fired Single-Pass Boiler<20 minute steam from cold. No hours-long warm-up or cool-down periods cuts energy usage.

Modulates to demand to further cut energy usage. Thermally stable design without

refractories, eliminates most repairs and maintenance costs up to 90%. Very long life, upwards

of 50 years, due to this unique design. From 40Bhp (1,700,000 BTU/hr.) up to 800Bhp

(27,000,000 BTU/hr.)


The Immersion-Fired Single-Pass Boiler Significantly Reduces Floorspace/Footprint and Volume for Easier Retrofit and More Compact New Installations

Up to 46% less space taken in your facility

Typical 300bhp Boiler 1,435 ft3,

very large volume and footprint

300bhp Immersion-Fired Boiler

769 ft3, drastically reduced

volume and footprint


160 ft2

103 ft2

New Technologies


2. Non-Ferrous Immersion-Fired Single-Pass Steam or Hot

Water Firetube Boiler

Good for up to 15psi applications trying to reduce

chemical additives costs.

Good for up to 15 psi applications needing untreated

water passed through from the water source.

New Technologies


3. “Parallel Positioning” or “Linkageless” Controls

Newer burners and burner/boiler packages provide this

technology.

New TechnologiesEssentially “fly by wire” as in modern aircraft. Instead of

mechanical cable/rod linkage, individual servos are

electrically-driven for better fuel and air flow adjustment.


New Technologies


4. Variable Frequency Drive (VFD) Motors and Pumps

Modulate to load and reduce electricity consumption

Motors run cooler, last longer

Many utilities provide rebates for the purchase and use

of VFD’s.

New Technologies

Variable Frequency Drive Motors and Pumps

A practical upgrade/retrofit in many cases.

Integral VFD


External VFD

New Technologies

5. Economizers – essentially stack/flue-mounted heat

exchangers that extract the last bit of heat and return

warm feedwater to the boiler for improved efficiency


New Technologies

6. Condensing Boilers

Started in Europe, and became mandated in the UK.

There is pushback

now due to the short

boiler life (5-10

years) and unrealized

efficiency or savings.


New Technologies


In a non-condensing boiler, about 15-20% of the heat vents out of the

stack/flue in the form of hot steam/water vapor and gases.

In a condensing boiler, a condenser recovers much of the lost heat. As

steam condenses into water, it puts heat back into the system.

In theory, this can increase overall efficiency from the 80-85% range to

as much as 96%.

New Technologies


In practice, for a condensing boiler to actually work and achieve this

efficiency, the water returning from your equipment and system back

to the boiler has to be below about 110 deg F. This allows the steam

in the boiler to condense into water.

For many applications the returning water is not cool enough, thus no

condensing occurs and the efficiencies are lost.

Real world lesson: Be sure you actually achieve above 110 deg F return

temperature if you wish to change to a condensing boiler.

Do I really have to use a boiler formy steam and hot water?


Boilers provide the practical, reliable and cost-effective steam and hot water to meet your operational needs.


Thank you.

Boilers: Basic Operations and NewTechnologies

DOUG RITCHIE, SELLERS MANUFACTURING CO. WWW.SELLERSMFG.COM

DRITCHIE@ SELLERSMFG. COM 859 -236 -3181 X222


mailto:[email protected]

mailto:[email protected]

boilers: basic operations and new technologies

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