Part 1 Condensing Theory - ashraeuae.org

CONDENSATION TECHNIQUE

Aerco Unical - 2015 1

Part 1

Condensing Theory

Condensing Technology



O2

CH4

O2

H2O

CO2

H2O

Condensing Technology Part 1: Theory

Simplified chemical equation for combustion



Higher and lower calorific/heating value

Two different calorific values in fuels:

1. Higher calorific/heating value (HCV)

the total amount of heat released during combustion, therefore also the latent heat of the water vapour of the discharged flues.

HCV = sensible heat + latent heat (or “hidden”)

2. Lower calorific/heating value (LCV)

the sensible heat that can be recovered from combustion without condensation.

LCV = sensible heat




Latent heat = 11% of gas combustion energy




Non-condensing boiler thermal overview Latent heat completely lost

• Qc thermal load pci*mc/h

• Qf flues loss in sensible heat

• Tf flues gross temperature

• Ta comburent air temperature

• CO2 % in flues

• f coefficient on fuel

• Qu working power

• Qd wet parts casing loss

• Qds dry parts thermal lossQc

QuQd + Qds




How to recover the Latent heat?




DEW POINT temperature, according fuel type

57

Natural Gas (95% CH4) Light Oil Con

de

nsin

g te

mp

era

ture

wa

ter

va

po

r [°

C]

Amount of CO2 [Vol. %]


10.5



We need to cool down flue gases < 57°C

How to do:

1. More efficient boiler’s heat exchanger

the total amount of heat released during combustion, therefore also the latent heat of the water vapour of the discharged flues.

2. Water return at a temperature lower than 55°C

the best case is with water return temperature at 30°C




Positive side effects of a colder boiler




pci

pcipcsPPdf

C100

1

B

CO

ATTP aff

2

1)(

sensible heat latent heat


Total boiler efficiency



Sensible heat loss

Pf = (tf - ta) * [(A1+B)/CO2]

conventional boilerPf = (190-15)*[(0,37+0,009)/10]

= 6,63 %

condensing boilerPf = (60-15)*[(0,37+0,009)/10]

= 1,8 %

around 5% difference




Condensing heat recovery, the “alpha” factor

Qcond = α* (HCV - LCV)

latent heat

light oil α

0,4 - 0,6

gas α

0,5 - 0,75

0,5 * 6% = 3% 0,6 * 11% = 7%




Total efficiency increase

Sensible heat increase on Pf and Pd

(lower flues temperature )

light oil gas

SENSIBLE 5% SENSIBLE 5%

+ +LATENT 3% LATENT 7%

_________________ __________________

TOTAL = 8% TOTAL = 12%




Example of condensing boiler efficiency

7.1040.77.97%

7.9765.035.10

35.1046.11

100

5.08.11%

2.98100

8.11%

condens

comb

SENSIBLE HEAT LATENT HEAT

97.7 7.0




Factors affecting condensation use

Condensationuse

ηHydraulic

connections

Boiler

design

characteristics

Fuel

Heating

system

Subsidy

Regulations

Laws

Return

temperature θand

load factor Ф




Comparing efficiencies (LCV)

Condensing boilers

High efficiency conventional boilers

Efficiency of standard boilers in 1975

Seaso

na

l eff

icie

nc

y [

%]

Boiler load [%]




Increasing efficiency in condensing boilers

- Latent heat recovery for condensation

- less dissipation through discharge gases

discharge flues temperature is lower, because sensible heat is completely transferred to the water inside the boiler

- lower dispersions for radiation

because the temperature of boiler water is lower




What about condensate water?




Condensing formation with different fuels

With the complete

condensation of

1 m3 of natural gas

it is possible

to recover:

1 kW

resulting in more11% heat and

1,6 litres

of condensate water

Higher calorific value. PCS

kWh/m3

Lower calorific

value. PCSkWh/m3

HCV/LCV HCV/LCVkWh/m3

theoretic condensation

kg/m3

district gas 5,48 4,87 1,13 0,61 0,89

nat. gas L 9,78 8,83 1,11 1,04 1,53

nat. HCH4

11,46 10,35 1,11 1,11 1,63

propanC3H8

28,28 25,99 1,09 2,29 3,37

buthan 37,22 34,31 1,08 2,91 4,29

light oil 10,68 10,08 1,06 0,60 0,88




Comparing pH values in nature

Light oil Natural gas Domestic water

Lemon juice

Rainwater Distilled

water

Seawater

Condensate from

condensing boiler

pH Value

Acid

Acid accumulator

Basic

Ammonia


Condensate water is acid



Materials used for condensing boilers

Stainless steel (AISI 316L or similar)


Aluminum alloy (Al-Si-Mg)

Corrosion resistant materials



Condensing Technology Part 2: Boiler features

Part 2:

Technical features

and Applications



Stainless steel – High water content


Capacities from 50 kW up to 2,000+ kW

Part 2: Boiler features

Same general features as conventional boilers, but more efficient.



Aluminum alloy – Low water content


Capacities from 50 kW up to 900 kW with modular system


A combustion chamber with burner, fan, gas valve and ignition

device is called module. A boiler can be made of many modules.




Model FS 981 488 GTB

Year 1922 2015

Power [HP] 530 670

Max speed [km/h] 40 360

Lenght [mm] 9,160 4,568

Weight [kg] 47,200 1,475

Engine made of Steel Aluminum

The opportunities of aluminum





ReliabilityNew concept of backup boiler



Backup boiler


Many plants are designed with a few boilers on duty

plus one as backup

- In case of boiler failure.

- In case of pick load demand

- etc



Up to 8 independent boilers in one

- The boiler’s capacity is usually

calculated according plant’s

max load.

- With a failure of one module

out of 4, it’s granted 75% of its

capacity

- This is not possible in boilers

with one burner only


If there is a failure in one or more modules, the other ones will

work normally.



Emergency functions


A. Emergency operation in case of

breakdown to the thermo-controller

E8, with activation of the heat

request at constant setpoint with

maximum capacity of 50%

B. Reset burner lockout

C. Remote alarm relay

D. ModBUS integrated




Modulationand cascade manager



Modulation


With several burners in one boiler is possible to achieve a

turn-down ratio impossible for single-burner models.

Turn-down modulation ratio up to 1:39



Modulation


1 module

100 % = 48 kW

1 module

38 % = 18

kW

108,2

18

100% =104. 9

pot. min = 108.4

P (kW)10

93

97103

109

(% pci)

20 30

T. Flow = 50°C

T. Return =

30°C

50

T. Flow = 80°C

T. Return =

60°C

1st decide the power and divide for the maximum n° of available

burner in order to work on the best efficiency point

2nd the cascade depending also to the working time of each

burner in order to have the same running time for every burner



Modulation


12 22 22 22 22 22

150

200

250

300

350

432

540

648

756

864

12 12 121212

100

0

50

100

150

200

250

300

350

400

450

500

550

600

650

700

750

800

850

900

E X

T 1

00

E X

T 1

50

E X

T 2

00

E X

T 2

50

E X

T 3

00

E X

T 3

50

E X

T 4

40

E X

T 5

50

E X

T 6

60

E X

T 7

70

E X

T 9

00

MIN

MAX



Cascade installation


With the cascade installation, the boiler output range can be

widened well over 900 kW, so multiplying output and modulation in

order to satisfy any design demand.




Pollution



Polluting emissions

Combustion polluting emissions:

- Dust or particulate

- Volatile Hydrocarbons CxHy

- Sulphur Oxides, SOx

- Carbon Oxide, CO

- Nitrogen Oxides, NOx (NO 90-95% e NO2 5-10%)




CO2 fuel emissions

0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

0,4

0,45

1

charcoal

hard coal

heavy oil

gas oil

natural gas




NOx formation (ozone and acid rain)

Thermal NOx

Permanence time

O2 partial pressure

Flame temperature

Formation procedure

Thermal

NOx

Available

NOx

Fuel

NOx

Nitrogen oxide and dioxide

formation




NOx formation

• In natural gas fuel, NOx

are practically absent;

• 90% comes from thermal

Nox: produced at the head

of the flame due to the

oxidation of the nitrogen

present in the air; the

process is highly

influenced by the

temperature.


Reverse flame boilers are the most polluting.



NOx formationIncidence factors

Partial O2 pressure: less O2 quantity in reaction zone less NOx formation





Air Filter

Smoke non return valve

Modulating Fan

Gas valve and Premix

Multigas

Burner

MODULE

(CASTING IN Al-Si-Mg)

Fla

me

Wate

r




Non-return valve

Air

Air

Air

Gas

Gas

Mix Air/Gas

Mix Air/Gas

PREMIX burner: the right quantity of air and gas is taken, mixed by the fan, then

pushed through the non-return valve to the burner for a perfect combustion



Combustion polluting emissions

- Emission < 35 ppm (NOx)

- Acoustic < 50 db (A)


The exhaust gases are immediately cooled down




Installationnew revolutionary opportunities



Boiler weight. Steel boiler vs aluminum boiler


350 kW boilers

Model 350 kW Reverse flame steel

boiler

Aluminum boiler

Boiler net weight [kg] 630 419

Water content [liters] 300 31

Boiler total weight [kg] 930 (without burner) 450 (burners included)

Large water content steel boilers, double the weight (or more) than aluminum boilers



Extremely compact: 1 MW on 1.5 m2 footprint

Condensing Technology Part 2: Boiler features1150 m

m

1448 m

m



Space saving


Sede Gas Natural-

Fenosa

Av. San Luis

(Madrid)

4x 900 Kw: 3600Kw

Minimum gap allowed between boilers is 40 cm only

Boiler room above is 3.5 MW in 20 m2 (5x4 m)



Waterproof casing IP 5x


Pneumatic control panel opening



Installation on rooftop


Advantages:

- Easier plant design

- Short chimney

- Reduced piping

No need of boiler room:

- Save valuable space

- Reduced safety requirements

Just beside chillers



Disassemble – pass through - assemble


Aluminum boilers are assembled, not welded.



Compact containerized installation




Solar panels and calorifiers integration




Part 3:

MODULEX

Condensing Technology Part 3: MODULEX



MODULEX: 15 pantent claims




MODULEX: BEYOND CONDENSING


GREEN BUILDING

- Emission <35 ppm (NOx),

- Acoustic <50 db (A)

RELIABILITY

- Built-in backup (several independent modules)

- 50% of capacity in Manual mode

- BMS and Remote alarm integrated

NEW INSTALLATION OPTIONS

- Outdoor / rooftop installation

- Compact solutions – space saving

HIGH EFFICIENCY

- Up to 109% efficiency

- Up to 1:39 turn down modulation



Part 4:

Global references




Phentagon - USA

Condensing Technology References



Apple store 5th Avenue - New York




His Highness Prince Ali - Jordan




National library - Alexandria of Egypt




Renoult Cleon - FRANCE




Condensing Technology Iconic global references

- AUSTRALIA: Hospital "AUSTIN" - Melbourne.

- AUSTRALIA: Crown Plaza – Casino & Luxury hotel.

- LATVIA: Ministry of Defence

- RUSSIA: KRASNODAR Palace

- IRAN: Shopping mall - Teheran

- ITALY: WHIRPOOL factory

- VATICAN (Rome): Pope’s palace




THANK YOU

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Part 1 Condensing Theory - ashraeuae.org