Maximizing Boiler Plant Efficiency. Presenter: Dan Watkins, LEED BD+C Sales Engineer Bornquist, Inc.

Maximizing Boiler Plant Efficiency Presenter: Dan Watkins, LEED BD+C Sales Engineer Bornquist, Inc.

Efficient Boiler Design Boiler Types Efficiency Definition Non-Condensing Condensing Maximizing Efficiency Understanding Efficiency Outdoor Reset Short Cycle Prevention Hybrid Systems

Efficient Boiler Design Combustion Efficiency 100 percent of efficiency minus the percentage of heat lost up the vent. Thermal Efficiency The combustion efficiency minus the jacket losses of the boiler. Based on ANSI Z21.13. For boilers 300,000 to 12.5 million Btu. A.F.U.E. The measure of annual efficiency of a boiler that takes into account the cyclic on\off operation and associated losses as it responds to changes in load. For boilers under 300,000 Btu

Efficient Boiler Design Non-Condensing Cast Iron Steel Tube Copper Fin Modulating 75-88% Efficiencies

Efficient Boiler Design Condensing Cast Aluminum Stainless Steel Cast Iron Dual Heat Exchanger 85-99% Efficiencies depending on operating conditions

MARKETING AND REALITY Thermal efficiency.can reach efficiencies of 98% - and more.. 98% EFFICIENT 3/20/12 Condensing Boilers 6

ENERGY CONTENT OF NATURAL GAS LATENT HEAT 10.2% SENSIBLE HEAT 89.8% Latent Definition: Latin for hidden Heat that can be measured or felt by a change in temperature 3/20/12 Condensing Boilers 7

NON-CONDENSING BOILER HEAT FLOW 3/20/12 Condensing Boilers 8

CONDENSING BOILER HEAT FLOW 3/20/12 Condensing Boilers 9

What is a Condensing Boiler? A condensing boiler is a boiler which has a heat exchanger that is made of materials which will withstand acidic condensate. 3/20/12 Condensing Boilers 10

MATERIAL CHOICES FOR CONDENSING BOILERS Materials on the market: Aluminum Alloy SA 240 316Ti 316L Cast Iron? Copper Tube w/ secondary heat exchanger 3/20/12 Condensing Boilers 11

Flue gas condensate Typical household sewage Oil Gas 0 1 2 3 4 5 6 7 8 9 10 11 12 Acidic ph-value Basic 0 1 2 3 4 5 6 7 8 9 10 11 12 Battery acid Gastric acid CORROSIVE FLUE GAS CONDENSATE ph Values of various fluids Lemon juice Vinegar Rain water Clean rain water Distilled water (neutral) Tap water Lake water Ammonia 3/20/12 Condensing Boilers 12

What about Efficiency? Condensing boilers are NOT 99% efficient all of the time. 3/20/12 Condensing Boilers 13

120 o F return water 100% input 87% efficiency Where is the condensation? 3/20/12 Condensing Boilers 14

Condensing/Modulating Boiler With efficiencies like this...... our customers have reduced their fuel bills by up to 80%. Now you can, too! 140 F EWT 120 F EWT 100 F EWT 80 F EWT 3/20/12 Condensing Boilers 15

LATENT HEAT RECOVERY WATER VAPOUR LIQUID Water vapor turns to liquid when it is reduced in temperature. 3/20/12 Condensing Boilers 16

HEAT RECOVERY FROM FLUE GASES Water vapor (steam) containing latent heat Simplified Chemical Combustion Formula: CH 4 + 2 O 2 CO 2 +2 H 2 O 3/20/12 Condensing Boilers 17

LATENT HEAT RECOVERY 1 pound of water Water vaporizing (Latent heat of condensation) 970 Btus Steam Ice melting (Latent heat of fusion) Ice 144 Btus 3/20/12 Condensing Boilers 18

WATER VAPOUR DEW POINT 3/20/12 Condensing Boilers 19

NATURAL GAS COMBUSTION +Excess air 1 part gas 10 parts air More excess air = Lower CO 2 % Lower C0 2 % = Lower dew point temperature Lower dew point temp. = Less condensation 3/20/12 Condensing Boilers 20

Dew point water vapor o F o C 140 60 131 55 122 50 113 45 104 40 95 35 86 30 77 25 WATER VAPOR DEW POINT Natural Gas (95% CH 4 ) CO 2 % of flue gas influences dew point temperature Higher CO 2 =Higher Dew point =More Condensation Lower CO 2 =Lower Dew point =Less Condensation 2 3 4 5 6 7 8 9 10 11 12 CO 2 in Vol % 3/20/12 Condensing Boilers 21

Heat Exchanger Design: PRIMARY HEAT EXCHANGER DESIGN SECONDARY HEAT EXCHANGER DESIGN 3/20/12 Condensing Boilers 22

PRIMARY HEAT EXCHANGER DESIGN 3/20/12 Condensing Boilers 23

SECONDARY HEAT EXCHANGER 3/20/12 Condensing Boilers 24

Efficient Boiler Design Condensing Boiler Design Guidelines Design system for lower water temperatures Use larger delta T s Radiant floor heat / snow melt Water Loop Heat Pumps Select boiler plant for small turndown capabilities Save initial cost by using both condensing and non-condensing boilers when possible

Outdoor Reset Efficient Boiler Design Designing a Reset Curve Cycle Efficiency How the cycle suffers Adjusting the differential Buffer Tanks Piping Systems Maximizing Efficiency

Efficient Boiler Design Outdoor Reset

Boiler Plant Cycle Efficiency 28

CHICAGO, IL 29

Cycle Efficiency Curve Analysis 30

Energy Use (Therms, DecaTherms, etc.) Energy Use Per Unit of Load (e.g., HDDs) Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun 31

Old Energy Use Per Unit of Load (e.g., HDDs) New Energy Use Per Unit of Load (e.g., HDDs) Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun 32

Old Energy Use Per Unit of Load (e.g., HDDs) New Energy Use Per Unit of Load (e.g., HDDs) Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun 33

Old Energy Use Per Unit of Load (e.g., HDDs) New Energy Use Per Unit of Load (e.g., HDDs) Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun 34

Energy Use (Therms, DecaTherms, etc.) Energy Use Per Unit of Load (e.g., HDDs) Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun 35

Energy Use (Therms, DecaTherms, etc.) Energy Use Per Unit of Load (e.g., HDDs) Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun 36

The E/L Curve Fast Calcula@on Billing Period Therms HDDs Therms/HDD December January February Best? March etc Total Therms Total HDD Total HDD x Best Therms/HDD = What s Possible Total Therms What s Possible = What Was Wasted 37

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To achieve HCE performance, you must 1 track small fracponal loads at high efficiency 2 make the efficiency rise as the load falls 3 size boilers so all loads fall within plant modulapon range 4 use low mass boilers for jockey service 5 use modulapng burners 6 oppmally match fuel input to real- Pme load 39

Piping Design Examples 40

Boiler Piping Examples

Boiler Piping Examples BOILER BOILER BOILER BOILER 42

Boiler Piping Examples

Boiler Piping Examples

Boiler Piping Examples

Boiler Piping Examples

Boiler Piping Examples

Boiler Piping Examples

Boiler Piping Examples

Boiler Piping Examples

Hybrid Boiler System

Buffer Tank Example Using a buffer tank to add 200 gallons will increase firing to almost 3 minutes for a 20 F delta T. Using reset on the system loop could allow for a 50 or 60 F delta T. Using a 60 F delta T would mean a minimum run time of over 8 minutes!

Buffer Tank Example 180 140

Buffer Tank Example 180 140

Buffer Tank Example Condensing Boiler Non- condensing Boilers

Buffer Tank Example BufferTank Non- condensing Boilers Condensing Boiler

Design Guidelines Utilize Buffer tanks and water temperature reset Design for long on/off cycles Boilers do not need to be same size/style Use small, modulating boilers as a jockey boiler Design for efficiency during light loads

Final Thoughts System design is typically more important than individual equipment selections. Energy retro-fits should be based potential savings and initial cost. Every building and every system is different, so there is no one-size-fits-all approach to Energy Saving Design.

Thank You! 60