## Cameron Abney and Associates Blog Review Formulas and Conversion Charts

sandrashedd Mar 14, 2014 12:29:28 AM

Cameron Abney and Associates Blog Review Formulas and Conversion Charts

A.            Boiler Formulas

Boiler Horse Power (HP):

BHP = (Lb/hr) * FE / 34.5

where Lb/hr is pounds of steam per hour and FE is the factor of evaporation.

Steam:

S=HP * 34.5 * t

where HP is boiler horsepower and t is time (h).

Cycle of Concentration of Boiler Water:

CYC=Bch / FCh

where  Bch  is  ppm  water  chlorides  and FCh is ppm feedwater chlorides.

Differential Setting (lb):

Delta S = P1 - P2

where P1 is the cutout pressure and P2 is the cut in pressure

Factor of Evaporation:

FE = SH + LH / 970.3

where SH is the sensible heat and LH is the latent heat.

Force (lb):

F=P / A

where P is pressure (psi) and A is area (in^2).

Horsepower (HP):

HP=(d * t) / (t * 33000)

where d is distance, F is force, and t is time.

Inches of Mercury (in):

InHG=P / 0.491

where P is pressure

Percent of Blowdown:

%BD=(PP - RP) / PP

where PR is popping pressure and RP is reseat pressure

Rate of Combustion (Btu/hr) RC=H / (Vf * t)

where H is heat released (BTU), Vf is volume of furnace (ft^3), and t is time (hr).

Return Condensate Percentage in Feedwater RC%=(MC – FC) / (MC – CC)

where MC is the makeup conductivity (μohms), FC is the feedwater conductivity (μohms), and CC is the condensate conductivity (μohms).

Static Head Pressure (lb)

SHP= Bpr * 2.31

where Bpr = boiler pressure (psi)

Temperature Conversions:

F to C

C = (F – 32) / 1.8

C to F

F = (1.8 * C) + 32

Total Force (lb)

TF = P*A

where P is pressure (psi) and A is the area of valve disc exposed to steam (sq. in.)

Water Column (in)

WC = P / 0.03061   where P is pressure (psi).

B. Combustion Chemistry

Flue gas analysis:

Boilerflue gas analysis is used todetermine

combustion efficiency.

CarbonDioxide (CO2)

Indicates completecombustion

Carbon Monoxide (CO)

Indicates incompletecombustion

Oxygen (O2)

Indicates thepresenceof excess air

Oxidesof Nitrogen(NOx)

A product of hightemperaturecombustion

Combustibles

Material thatburns whenexposed to oxygen andheat

It is typical to target oxygen levels of 8% in low fire and 3% in high fire for gas fired burners.

It is typical to target oxygen levels of 6% in low fire and 4% in high fire for oil fired burners.

Johnston Boiler Company  recommends  no greater level than 200 ppm of Carbon Monoxide in its burner operation. The acceptable “Industry Standard” level is 400 ppm or less.

Johnston Boiler Company recommends zero combustibles for a gas fired burner.

Johnston Boiler Company recommends a maximum #2 Smokespot (Ringelmann Chart) in its oil fired burner.

Air Properties:

For a burner originally adjusted to 15% air, changes in combustion air temperature and  barometric pressure cause the following in excess air:

Air Temperature

BarometricPressure (In.HG)

ResultingExcess Air %*

40

29

25.5

60

29

20.2

80

29

15.0

100

29

9.6

120

29

1.1

80

27

7.0

80

28

11.0

80

29

15.0

80

30

19.0

40

31

34.5

60

30

25.0

80

29

15.0

100

28

5.0

120

27

-5.5

* Expressed as a percent of the Stoichiometric air required.

C. Energy Loss From Scale Deposits

ENERGY LOSS

FROM SCALE DEPOSITS IN BOILERS

SCALE THICKNESS(INCHES)

EXTRA FUEL COST(PERCENT)

1/32

8.50

1/25

9.30

1/20

11.10

1/16

12.40

1/8

25.00

1/4

40.00

3/8

55.00

1/2

70.00

Related Articles:

http://www.boilerroomservices.com/