BOILER FORMULAS
BOILER HORSE POWER
What is the boiler horsepower of a boiler generating 21,500 lbs
of steam per hour at 155 psi?
The factor of evaporation is 1.08.
BHP = (LB/HR*fe)/34.5
| BHP |
boiler horsepower |
BHP = (LB/HR*fe)/34.5 |
| Lb/Hr |
pounds per hour |
BHP = 21500 * 1.08 / 34.5 |
| Fe |
factor of evaporation |
BHP = 673 |
CYCLE OF CONCENTRATION OF BOILER WATER
What is the cycle of concentration if the chloride content of boiler
water is 186 ppm and the feedwater chloride content is 38 ppm?
CYC = Bch/FCh
| CYC |
cycles of concentration |
CYC = Bch/FCh |
| Bch |
boiler water chlorides (ppm) |
CYC = 186 / 38 |
| FCh |
feedwater chlorides (ppm) |
CYC = 4.89 |
DIFFERENTIAL SETTING
What is the differential setting of an automatic pressure control that
turns the burner ON at 80 psi and OFF at 105 psi?
delta S = P1 - P2
| delta S |
differential setting delta |
S = P1-P2 |
| P1 |
cut-out pressure delta |
S = 105 - 80 |
| P2 |
cut-in pressure delta |
S = 25 |
FACTOR OF EVAPORATION
Water enters the boiler at 225°F. The boiler pressure is 100 psi
and the boiler water temperature is 338°F. The latent heat is 881
Btu. What is the factor of evaporation?
FE = SH + LH / 970.3
| FE |
factor of evaporation |
FE = SH + LH / 970.3 |
| SH |
sensible heat |
FE = ((338 - 225) + 881) / 970.3 |
| LH |
latent heat |
FE = 1.02 |
| 970.3 |
latent heat of evaporation of water at 212°F. (constant) |
|
FORCE
What is the force of 260 lbs of pressure exerted on 8 sq. in.?
F = P/A
| F |
force (psi) |
F=PA |
| P |
pressure |
F=260/8 |
| A |
area |
F=32.5 |
HORSEPOWER
What is the horsepower of a pump that moves 450 lbs of water against
a discharge head of 220 ft. In 1 minutes? Disregard friction and other
losses.
HP = (d * F) / (t * 33,000)
| HP |
horsepower |
HP = (d * F) / (t * 33,000) |
| d |
distance |
HP = (220 * 450) / (1 * 33,000) |
| F |
force (lb) |
HP = 3 |
| t |
time (minutes) |
|
| 33,000 |
constant |
|
INCHES OF MERCURY
How many inches of mercury are there at an atmospheric pressure of 14.5
psig?
in. HG = P / 0.491
| Hg |
inches in mercury |
in. Hg = P / 0.491 |
| P |
pressure (psi) |
in. Hg = 14.5 / 0.491 |
| 0.491 |
constant (psi @ 1 in. of Hg) |
in. Hg = 29.53 |
PERCENT OF BLOWDOWN
What is the percent of blowdown for a safety valve set to pop at 300psi
and reseat at 275 psi?
%BD = (PP - RP) / PP
| %BD |
percent of blowdown |
%BD = (PP - RP) / PP |
| PP |
popping pressure |
%BD = (300 - 275) / 300 |
| RP |
reseat pressure |
%BD = 8.33% |
RATE OF COMBUSTION FOR GASEOUS OR LIQUID FUELS
A scotch marine boiler has a furnace volume of 45.5 cu. ft. if
3825.2 cu. ft. of natural gas is burned per hour and each contains 1100
Btu, what is the rate of combustion?
RC = H / (Vf * t)
| RC |
rate of combustion (Btu/hr) |
RC = H / (Vf * t) |
| H |
heat released (Btu) |
RC = (3825.2 * 1100) / (45.5 * 1) |
| Vf |
volume of furnace (cu. ft.) |
(cu. ft.) RC = 92477.36 |
| t |
time (hr) |
|
RETURN CONDENSATE PERCENTAGE IN FEEDWATER
What is the return condensate percentage in feedwater if the makeup
conductivity is 834 µ ohms, the feedwater conductivity is 185
µ ohms, and the condensate conductivity is 65 µ ohms?
RC% (MC-FC) / (MC-CC)
| RC% |
return condensate % |
RC% = (MC-FC) / (MC-CC) |
| MC |
makeup conductivity ( µ ohms) |
RC% = (834 - 185) / (834 - 65) |
| FC |
feedwater conductivity ( µ ohms) |
RC% = 84.40% |
| CC |
condensate conductivity ( µ ohms) |
0.84 |
STATIC HEAD PRESSURE
What is the static head pressure of a boiler operating at 275 psi?
SHP = Bpr * 2.31
| SHP |
static head pressure |
SHP = Bpr * 2.31 |
| Bpr |
boiler pressure (psi) |
SHP = 275 * 2.31 |
| 2.31 |
multiplier |
SHP = 635.25 |
STEAM
How much steam will a 150HP boiler make in 2.5 hours?
S = HP * 34.5 * T
| S |
steam |
S = HP * 34.5 * t |
| HP |
horsepower |
S = 150 * 34.5 * 2.5 |
| 34.5 |
constant (lb/hr) |
S = 12937.50 |
| t |
Time (hr) |
|
TEMPERATURE CONVERSIONS
| °F to °C |
|
Convert 92° to °C |
| °C = |
(°F - 32) / 1.8 |
°C = (°F - 32) / 1.8
°C = (92-32) / 1.8
°C = 33.33 |
| °C to °F |
|
Convert 30°C to °F |
| °F = |
(1.8 * °C) + 32 |
°F = (1.8 * °C) + 32
°F = (1.8 * 30) + 32
°F = 86 |
TOTAL FORCE
What is the total force of 120 psi acting on 4 sq. In?
TF = P*A
| TF |
total force (lb) |
TF = P*A |
| P |
pressure (psi) |
TF = 120 * 4 |
| A |
area of valve disc exposed |
TF = 480 |
| |
to steam (sq. in.) |
|
WATER COLUMN
How high is a column of water that exerts 42.43 psi at the bottom
of the column?
WC = P / 0.433
| WC |
water column |
WC = P / 0.433 |
| P |
pressure |
WC = 42.43 / 0.433 |
| 0.433 |
constant (force per 1 ft of |
WC = 97.99 |
| |
water depth) |
WC = 97.99 |
