®
e a s y
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a
S u n d a y
AVAL
m o r n i n g …
technical book
1
®
e a s y
l i k e
a
S u n d a y
AVAL
m o r n i n g …
steam
®
e a s y
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a
S u n d a y
AVAL
m o r n i n g …
Garioni Naval’s technical notebooks have been studied to offer a useful tool for the
technical offices and for the users of steam, pressurized water and thermal oil.
We obviously do not have the presumption to want to teach how things should be
done. We just want to put at disposal of those people that wish to increase their
knowledge in this sector, or find new information, our experience matured in
many years of study and hard work.
We warmly hope that what is written in these "technical books" will allow every
reader to be able to work with ease and serenity and to avoid, where possible,
to fall in errors that others, previously, have unintentionally committed in order to
arrive to a certain knowledge level of the Termotecnics sector.
This series of notebooks will be published in two editions, one in Italian and the
other in English.
We thought, with the purpose to avoid any possible confusion, that it was more
practical and technically more appropriate, not to mix the two languages.
The collection is dedicated to all those people whom have contributed, and that
are still contributing, to GARIONI NAVAL’S development and growth.
If you are interested to receive all the issues, please apply compiling in each part
the enclosed form, by Internet through our web site www.garioninaval.com or by
e-mail at [email protected]
G2
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e a s y
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m o r n i n g …
Steam, a traditional but at the same time modern and efficient instrument,
is practically irreplaceable regarding petrochemical, chemical, paper,
dyeing, pharmaceutical, food, canning, rubber and plastic industries etc.
It is also indispensable in the civil sector for sterilising in hospitals and
clinics, it is used as a preference in canteens and laundries and in air
conditioning plants (on industrial level, where it is often used for heating).
Again it has a wide and irreplaceable use in generating power using
turbines, pumps and alternators in large heating plants and onboard ships.
Wherever there is a need to produce, pump and utilise both thermal
energy and pressure, steam is the ideal solution.
What advantages does it have and which are the reasons for this?
Above all, steam can be produced fairly easily and comes from water
which, at least in relation to the present or near future global production
needs of steam, is luckily still available in large quantities and at
economically advantageous conditions, apart from the fact that in steam
plants continuos recycling is applied and recovery can be almost one
hundred per cent.
Steam has a very high ponderal heat content which means tubes and user
units having to support a light load, which also means movable equipment
with excellent exchange coefficient, compact and economic.
Steam circulates naturally without requiring accelerators, temperatures
can be high at quite low pressures which means a relatively safe means
and fairly easy to deal with.
Temperature or pressure regulations can be carried out using simple twoway valves; above all it has the advantage of being extremely “flexible”
meaning that it adapts well to later variations and changes, not like other
fluids such as water, superheated water, diathermic oil, etc..
Of course the above mentioned becomes more valid concerning steam
plants which have been rationally designed and constructed, above all
regarding recovering energy.
This automatically leads to the fact that trained technicians with a good
knowledge of the subject should be called in because, although steam is
not so complex as other fluids, a good theoretical preparation and
practical know-how are required.
G3
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C ONVERSION TABLE FROM T RADITIONAL
N EW I NTERNATIONAL S YSTEM U NITS
TO
Pressure
Unity
Measurement
Symbol
Pa
bar
at
mm Hg
kgf/m2
Pascal
Pa
1
10-5
1,0197x10-5
0,0075
0,10197 0,145x10-3 0,02088
0,00401 0,295x10-3 0,335x10-3
Bar
bar
105
1
1,0197
750,07
10197
14,505
2088
401,46
29,530
33,456
Atmosphere=kgf/m2
at
98070
0,9807
1
735,56
10000
14,223
2048,16
393,71
28,960
32,808
Millimetres of Hg
mm Hg
133,32 1,332x10-3 1,3595x10-3
1
13,595
0,0193
1,392
0,5353
0,0394
0,0446
kilograms per m2
kgf/m2
9,807
9,807x10-5
10-4
0,0735
1
0,00142
0,205
0,0394
0,0029
0,0033
Pounds per in2
psi
6894,14
0,06894
0,0703
51,719
703,07
1
144
27,683
2,0362
2,3069
Pounds per ft2
lbf/ft2
47,876 4,7876x10-4 4,8824x10-4
0,7183
4,8824
0,00694
1
0,1922
0,01414
0,01602
Inches of w.c.
in w.
249,09
0,00249
0,00254
1,868
25,4
0,03614
5,203
1
0,07355
0,0833
Inches of Mercury
in Hg
3386,36
0,03386
0,03453
25,4
345,34
0,4912
70,731
13,595
1
1,1329
Feet of w.c.
ft w.
2989
0,02989
0,03048
22,42
304,8
0,4334
62,43
12
0,8827
1
psi
bf/ft2
in w.
in Hg
ft w.
Energy
G4
Unity
Measurement
Symbol
J
kgf/m
Cal (kcal)
Wh
CVh
ft.lbf
Btu
Joule
J
1
0,10197
0,2388x10-3
0,2778x10-3
0,378x10-6
0,7375
0,9478x10-3
Kilogrammeter
kgf/m
9,807
1
2,342x10-3
2,724x10-3
0,370x10-5
7,233
9,295x10-3
Kilocalorie
Cal ( kcal)
4186,80
426,92
1
1,163
1,581x10-3
3087,6
3,9683
Watt-hour
Wh
3600
367,08
0,8605
1
1,360x10-3
2654,87
3,413
Horsepower hour
CVh
2647,8x103
269,91x103
632,53
735,5
1
1952,92x103
2512,2
Pound Foot
ft.lbf
1,356
0,1383
0,3238x10-3
0,3767x10-3
0,512x10-6
1
1,2853x10-3
Btu (Ist)
Btu
1055,06
107,58
0,2520
0,2930
0,398x10-3
778,03
1
®
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m o r n i n g …
basic references
to heat theory
Temperature and heat
The temperature of a body is the degree of heat it
possesses, that is to say the thermal state of that same
body in a specific moment.
Temperature is measured by thermometers.
Calorie (Kcal) is the amount of heat a body possesses.
A calorie is the amount of heat required to raise the
temperature of 1 Kg of water by 1°C (to be exact from
14°C to 15°C).
Difference between temperature and heat
We can say that the two tanks have reached the same
temperature of 80°C but one required 3500 Kcal and the
other 7000 Kcal. There fore, in order to bring the two
tanks at the same temperature of 80°C, we must consider
that one requires 5 times more calories than the other
(35000÷7000=5).
Specific heat
The specific heat of a mass is the amount of heat necessary
to raise the temperature of 1 Kg of said mass by 1°C.
The quantity of heat required to raise the temperature of
a certain weight of a mass by 1°C is not the same for all
masses.
SPECIFIC HEAT OF SOME SOLID AND LIQUID ELEMENTS
water
Lets suppose we have to heat the water in two tanks of 80°C.
One tank contains 500 l of water, that is 500 Kg.
The other contains 100 l of water, that is 100 Kg.
Each tank reaches the same temperature of 80°C.
Kcal/Kg
1,00
heavy oil
“
0,50
olive oil
“
0,45
bricks
“
0,20
wood
“
0,57
iron
“
0,11
lead
“
0,03
copper
“
0,09
Bearing in mind the definition of calorie and taking for
granted that the water at the beginning was 10°C, in
order to increase 1 Kg of this water from 10°C to 80°C
we must administer: 80 – 10 = 70 calories.
As in order to increase from 10°C to 80°C 500 Kg of
water we must administer:
80 – 10 = 70
70 x 500
= 35000 Kcalories
Example: raise the temperature of 500 Kg of water from
20 °C to 70°C. Specific heat of water = 1
70-20 = 50°C 50 x 1 x 500
=25000 Kcal
The other tank contained 100 Kg of water, in order to
increase it from 10°C to 80°C it necessitates:
80 – 10 = 70
70 x 100= 7000 Kcalories
Example: raise the temperature of 500 Kg of heavy oil
from 20 °C to 70°C. Specific heat = 0.5
70-20 = 50°C 50 x 0.5 x 500 =12500 Kcal
G5
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Sensible heat
Total heat of steam
The heat which produces a temperature increase when it
penetrates into a body is called sensible heat.
Regarding boilers, this means that the heat which passes
from the furnace to the water heating is always sensible
heat. The complete name is: sensible heat of water.
Therefore, at atmospheric pressure a total of 640 Kcal is
needed to transform 1 Kg of water into steam.
•
•
•
To bring it to the boiling point it requires :100
to transform it into steam it requires
:540
the total heat of 1 Kg of steam will be
:640
Kcal +
Kcal =
Kcal
The temperature of water and steam remaines at 100°C.
We have already seen that the steam generated in our
open pot contains two types of calories.
There is the water’s sensible heat, to which is added its
latent heat that was needed to convert the water into
steam.
By heating 1 Kg of water in an open pot reach a
temperature of 100°C its heat content is 100 Kcal/Kg.
We will have:
Temperature of water
= 100°C
Heat content or sensible heat of water = 100 Kcal/kg
Latent heat
If we continue to add heat to the water, its heat content and
temperature will not increase further but the water will
begin to boil: it has reached its boiling point at 100°C.
By adding further heat to the water a change of state
takes place: from a liquid to a gaseous state. Boiling water
forms steam, water vapour this means that the extra heat
added to the water after it started to boil and which
consequently caused its transformation into steam is latent
heat (the complete name is heat of water vaporisation).
The quantity of latent heat is measured in calories.
The total heat contained in the steam is therefore made up
of sensible and latent heat.
It can be seen that the quantity of latent heat is much
higher than the quantity of sensible heat. In each Kg of
steam at 100°C there are roughly 100 cal of sensible heat
and 540 cal of latent heat with a total heat of 640 cal.
Whatever is the quantity of steam the proportions remain
the same.
For example, if instead of 1 Kg of steam we had 100 Kg
and we examined these findings, all we need to do is to
multiply what we said previously by 100.
Production of steam under pressure
The atmosphere exerts a pressure on everything that
exists on the earth’s surface and this pressure is exerted
in all directions: about 1.033 Kg for every centimetre of
surface.
If we now go back to the steam which was starting to
come out of the pot we can see that it is submitted to
atmospheric pressure, that is by this pressure which
surrounds it; a pressure of 1.033 Kg/cm2.
The temperature of the steam at this atmospheric pressure
is the same as the boiling water, also at atmospheric
pressure and that is 100°C.
As long as the pot remains open and the steam can exit
freely, everything remains at atmospheric pressure and at
the specific corresponding temperature.
G6
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S u n d a y
Sensible heat at
atmospheric pressure
:100 Kcal/Kg
Sensible heat at
a pressure of 10 atm
:186 Kcal/Kg
AVAL
m o r n i n g …
Difference : +86 Kcal/Kg
Latent heat at
atmospheric pressure
:540 Kcal/Kg
Latent heat at
a pressure of 10 atm
:478 Kcal/Kg
Difference : -62 Kcal/Kg
In order to clarity here following are the values again:
• internal
and external pressure of the pot
• steam pressure
• temperature of water in pot
• temperature of steam
:1.033 Kg/ cm2
:1.033 Kg/ cm2
:100°C
:100°C
Now, lets cover and seal the pot. By continuing to
administer heat, steam is produced; the more steam is
produced inside this container the more it is subjected to
compression in order to find room and, as it is compressed
it attempts to move in all directions, exerting pressure on
everything around it. In this way, besides exerting pressure
on the internal surfaces of the pot, the steam creates
pressure on the surface of the water.
Increasing the pressure on the surface of the water causes
an increase in the boiling temperature.
Whereas at atmospheric pressure (1.033 Kg/ cm2.) water
boils when it has reached a temperature of 100°C, we find
that, for example, at a pressure of 10 Kg/ cm2.
The boiling temperature increases to 184°C.
It can be immediately seen that in order to keep the water
boiling and consequently to produce steam at this higher
temperature, a higher quantity of sensible heat has to be
supplied.
On the other hand at these higher temperatures and
pressures, the quantity of latent heat necessary to
transform the boiling water into steam is less.
In reference to the two examples given above we will have:
Total heat at
atmospheric pressure
:640 Kcal/Kg
Total heat at
a pressure of 10 atm
:664 Kcal/Kg
Difference : +24 Kcal/Kg
Water temperature at
atmospheric pressure
:100 °C
Water temperature at
a pressure of 10 atm
:184 °C
Difference : +84C°
If we compare the two situations we will see that: the total
heat has increased but only slightly ( +24 Kcal/Kg), the
sensible heat has increased a lot (+86 Kcal/Kg) but the
latent heat has decreased (-62 Kcal/Kg).
In conclusion, when steam pressure increases more
total heat but not much, (and the increase becomes less
and less as the pressure increases), more sensible heat
is available but there is less latent heat.
When steam pressures decrease less total heat, but
only slightly less, less sensible heat will be available,
but there will be more latent heat.
Steam pressures are expressed in Kg/ cm2 or bar and are
divided into relative and absolute pressures.
In the technical field the one usually referred to is
relative pressure.
If relative pressure has to be changed into absolute
pressure, the level of relative pressure of atmospheric
pressure has to be increased. (+1).
The relative pressures are the pressures indicated by
normal manometers installed in every boiler.
G7
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Space occupied by steam
- At the relative pressure of 1Kg/cm2 steam occupies
0.177 m3.
(specific volume)
The space occupied by a certain weight of steam will
depend on its pressure.
If we have 1 Kg of water and we transform it all into
steam, we will have exactly 1 Kg of steam.
- At the relative pressure of 1Kg/cm2 dry saturated steam
occupies 0.881 m3.
P HYSICAL
bar
G8
kg/cm2
assolute
bar
kg/cm2
But as pressure increases we find that the steam occupies
less and less space and that it gradually gets compressed
as the pressure increases.
CHARACTERISTICS OF SATURATED STEAM
PRESSURE
relative
In both cases we started with exactly the same amount of
water and in both cases we transformed the water into
exactly the same weight of steam.
TEMPERATURE
k
°C
SPECIFIC HEAT SENSITIVE
VOLUME
OF WATER
m3/kg
LATENT HEAT
TOTAL HEAT
kJ/kg kcal/kg kJ/kg kcal/kg kJ/kg kcal/kg
®
e a s y
P HYSICAL
l i k e
a
S u n d a y
AVAL
m o r n i n g …
CHARACTERISTICS OF SATURATED STEAM
PRESSURE
relative
bar
kg/cm2
assolute
bar
kg/cm2
TEMPERATURE
k
°C
SPECIFIC HEAT SENSITIVE
VOLUME
OF WATER
m3/kg
LATENT HEAT
TOTAL HEAT
kJ/kg kcal/kg kJ/kg kcal/kg kJ/kg kcal/kg
www.garioninaval.com
G9
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m o r n i n g …
ENTHALPY
SPECIFIC
G10
OF SUPERHEATED STEAM
HEAT OF SUPERHEATED STEAM
®
e a s y
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a
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AVAL
m o r n i n g …
reverse flame fire tube
steam boiler
Operating Principale
The combustion products flow through the boiler is furnace,
then, as the furnace is the closed bottom type, they return
in the opposite direction along the circumference on the
external wall and reach the front inversion chamber
housed in the refractory material of the door.
The fire return tubes are arranged in groups around the
boiler furnace is exit from the front inversion chamber
and connected into the rear fumes chamber from where
they are introduced into the stack.
Inserted inside the fire return tubes are high temperature
resistant stainless steel helicoidal bars. The aim of these, so
called “turbulence” bars, is to increase the turbulence of the
fumes and therefore increase the heat exchange between
themselves and the water circulating around them. The
presence of “impellers” and the particular direction the
fumes have to take, makes natural draft through the boiler
with the furnace off almost nil.
The loss in yield, due to intermittence, is therefore very
restricted.
For the same reason the size of the boiler must be
calculated so that, when operating the fan, it supplies
sufficient pressure to win the losses in load of the boiler
notwithstanding the natural draft.
Regarding the water/steam side, the boiler has a top
steam chamber kept at a certain level, which aim is to
create sufficient “ evaporation surface” to produce heat.
G
Cross section of: reverse flame fire tube steam boiler.
G11
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m o r n i n g …
three passes wet back
steam boiler
Operating Principale
The boiler is always of the return tube type, but instead
of being equipped with a return furnace it is equipped
with a front fume return chamber placed at the exit of the
furnace.
This return chamber, called “stove”, is, in the more
modern models, completely washed with water to
decrease the loss through irradiation and to avoid
excessive overheating of the walls. In the stove, the fumes
enter the tube nest and return along the front wall of the
boiler where they enter the second return chamber
housed in the refractory coating of the front door, where
they enter the second tube nest and connect up to the
rear fume chamber and from here exit through the stack.
The furnace, in these type of boilers, is often corrugated
to absorb heat dilations.
These generators are normally used to produce over 4/5
tons/h of steam when the increase in length of the
furnace makes correct distribution of the heat produced
inside the furnace itself more difficult.
It is clear that in these cases, as it is a through furnace,
the only exit for the fumes is in the top section and
therefore there is a better exploitation of the walls.
Usually the exchange surfaces of these generators are,
power being equal, better than those with fire return
tubes.
G
Cross section of: three passes wet back steam boiler.
G12
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m o r n i n g …
two passes dry back
steam boiler
Operating Principale
The boiler is of the fire tube passes type, but the reversing
flame chamber, covered with refractory suitable for high
temperatures, conveys the gasses that have completely
passed through the furnace, in the tubes of the second
and last pass, before being expelled from the chimmey in
the front fume chamber.
Anyhow, the passing furnace allows to exploit all the
exchange surface of the furnace apart from the load that
the generator is submitted to.
Therefore, you can obtain an excellent efficiency also at
low loads.
Due to the furnace’s length, where are exchanged 60/70%
of the heat produced by combustion, these generators are
normally used for steam productions up to 5 ton/h.
G
G
Cross section of: two passes dry back steam boiler.
G13
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m o r n i n g …
water tube boiler
Operating Principale
Water side
With the increase in power, and in particular operating
pressures, the use of a water tube boiler becomes
problematic since the high pressures require the walls of the
tube nest to be thicker making the construction of such
boilers uneconomic.
In these cases, water-tube steam generators are preferable
where the water and steam, instead of being contained by
the cover, are confined within the tubes, therefore allowing
much higher operating pressures.
The boiler is constructed using the classic form of two
cylindrical bodies, a prismatic combustion chamber made
up of tubes placed at a tangent to each other with water
flowing through them. The combustion develops in this
combustion chamber which exchanges heat by irradiation.
The other section of the boiler is made up of the two
horizontal cylindrical bodies, placed one above the other.
The function of the top cylinder is to collect the water/steam
mixture coming from the boiler tubes and to separate the
steam from the water.
The bottom one, on the other hand, collects the water for the
tube nest tubes and furnace chamber.
The two cylindrical bodies are connected to each other
as follows:
1) by a nest of vertical tubes which form the convection heat
exchange zone;
2) by a group of tubes at a tangent forming a “D”, welded
together and inserted into the cylinder bodies along a
generator forming a part of the combustion chamber for
heat exchange by irradiation.
3) By walls of welded vertical tubes at a tangent and
connected to two manifolds to form the front and rear
closure of the combustion chamber. The opening for the
housing of the burner is made in the front wall.
• The water reaches the top cylindrical body and is
distributed internally through a tube with carefully positioned
holes to ensure uniform distribution along all the body;
• The heat flow in the combustion chamber and tube nest
draws in the water which is then distributed through all the
tubes according to their role in the exchange.
• The water/steam mixture, formed in the tubes, reaches
the top cylindrical body where the steam is separated and
removed, whereas the water is recycled.
G14
Gasses
• Combustion which takes place in the “D” shaped chamber
is the pressurized type. The hear exchange takes place in
this chamber though irradiation due to the high temperature
of the flames and their brightness.
The combustion products exit the chamber through the
special outlet leading into the tube nest. The turbulence
caused by the hot fumes moving between the tubes creates
convection heat exchange with the water-steam mixture
circulating inside the tubes; this lowers the temperature of the
fumes exiting the generator.
These generators are usually used either when the operating
pressure required is more than 15 bar or when the
production of steam exceeds 10/12 Tonn/h.
Controlled Circulation type
For small capacities, up to 8 tonn/h are used generators in
which the water circulation in the tubes is granted by a
pump and the evaporation is carried out, during its crossing,
in the same tubes.
These are water tube controlled circulation steam.
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G
G
Cross section of a controlled circulation water tube steam generator.
G
Cross section of a natural circulation steam generator.
G15
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m o r n i n g …
steam boilers:
general thermo-technical data
Characteristic elements of steam generators
Production capacity:
This is the quantity of steam produced in 1 hour and it is
measured in Kg/h. It is of course necessary to indicate the
physical state of the steam (pressure, temperature). In this
case, with the thermal content of a Kg of produced steam
known, it could be more conveniently expressed as a
power unit kW or Kcal/h.
Specific power:
This is the ratio between the kilograms of steam produced
per hour and the heating surfaces. It represents the
kilograms of steam produced in one hour for every square
meter of heated surface; it is measured in Kg/m2/h.
Production of steam on the basis of the heating surface
BOILERS
TYPE OF BOILER
STEAM PRODUCTION
Kg/h per m2 SUP
CORNISH
18
BOILERS CORNISH
WITH FIRE RETURN
20
BOILERS HORIZONTAL SE MI-FIXED
25
BOILERS
VERTICAL SE MI-FIXED
20
BOILERS
MARINE TYPE1
8
PRESSURIZED BOILERS. Pressure from 1 to 5 ATE
from 29-31.000 Kcal/m2/h equal to:
53-58
PRESSURIZED BOILERS. Pressure from 8 to 15 ATE
from 29-31.000 Kcal/m2/h equal to:
Tag pressure:
This is the maximum rated pressure the generator can
operate.
The measuring unit is the bar or Kg/ cm2 (ate). The rate
pressure can be obtained from the logbook of the
equipment and from the stamp in the centre of the plate.
Operating pressure:
This is the pressure, lower or equal to the tag pressure, at
which the generator operates.
48-50
Thermal volumetric load of the combustion chamber
This is the ratio between the quantity of heat developed
from combustion in the unit of time and the volume of
the combustion chamber. It is measured in Kcal/m3/h.
TVL= (G x Pci) : V
TVL= Thermal volumetric load
(Kcal/m3/h)
G=
Heating surface:
This is the sq. meters of area of the surface in contact, on
one side with the fumes and on the other by the water; it
is measured on the part in contact with the fumes.
The heating surface is the
sum of the Surfaces of the
combustion chamber and
the surfaces of the tubes in
the nest.
The internal surface of the
tubes must be taken into
consideration.
G16
combustion capacity
(Kg/h – m3/h)
LCV= lower calorific value of
fuel
(Kcal/Kg – Kcal/ m3)
V=
Volume of furnace (m3)
Example:
Boiler with natural gas burner gauged for a capacity of 258 m3/h
Lower calorific value of natural gas
: 8500 Kcal/m3
Volume of combustion chamber
: 2 m3
TVL ( 258 x 8500) : 2 = 1,096,500 Kcal/ m3/h
®
e a s y
THERMAL VOLUMETRIC LOAD OF THE
COMBUSTION CHAMBER. PRESSURIZED BOILERS
RATED PRESSURE
800.000
from 800.000
to 1.200.000
Surface thermal load of combustion chamber:
This is the ratio between the quantity of heat developed in
the combustion chamber in the unit of time and the
heating surfaces of the combustion chamber; it is
measured in Kg/m2/h.
SURFACE THERMAL LOAD OF
COMBUSTION CHAMBER
Kg/m2/h.
CORNISH AND MARINE
VERTICAL FIRE-TUBE
HORIZONTAL SE MI-FIXED
10.000
11.000
15-20.000
PRESSURIZED BOILERS. RATED 1 to 5 ate
PRESSURIZED BOILERS. RATED FROM 8 to 15 ate
27-35.000
29-31.000
BOILERS
BOILERS
BOILERS
S u n d a y
AVAL
m o r n i n g …
Vaporisation index
from 1.000.000
to 1.800.000
WATER-TUBE BOILERS
a
Kg/cal m3/h
1 ate
FIRE-TUBE BOILERS
l i k e
This is the ratio between the mass of steam produced and
the quantity of fuel burned in the same moment.
It represents the kilograms of steam which can be
obtained from burning 1 Kg of fuel.
For pressurized boilers this can be defined fairly
accurately as:
1 Kg of heavy oil
(9600 cal) can produce
12-14 Kg steam
1 Kg of diesel fuel (10200)
can produce
13-15 Kg steam
1 Nm3 of natural gas (8500)
can produce
10-11 Kg steam
Characteristics of steam boiler’s feed
water pump
Generator yield:
This is the ratio between the heat transmitted to the fluid
and the heat developed by combustion.
Example: Steam boiler, rated pressure: 12 ate.
Capacity burned at burner: 1.150.000 Kcal/h
Capacity yielded to water: 1.000.000 Kcal/h
P = Pump operating pressure = 1,2 x rated boiler
pressure
Q = Pump operating capacity = 2 x maximum delivery
(Kg/h) boiler steam production
Conversions tables of power units
Interpretation of concepts Kcal/h – Kw/h – Hp/h
Yield: 1.000.000 = 0.869 = 86.9%
1.150.000
TYPE OF BOILER
CORNISH
STEEL BOILERS:
YIELD %
68-72
FIRE-TUBE CORNISH
76-80
MARINE TYPE
70-75
SEMI-FIXED HORIZONTAL
77-82
SEMI-FIXED VERTICAL
68-72
MULTI-TUBULAR WATER TUBES
84-87
PRESSURIZED
84-87
FORCED CIRCULATION
90
steam prod.
capacity
capacity
steam prod.
Kg/h
Kcal/h
Kw/h
Hp/h
125
300
550
750
1,000
2,000
3,000
75,000
180,000
330,000
450,000
600,000
1,200,000
1,800,000
87
209
383
523
697
1,393
2,090
116.6
280
514
701
935
1,868
2,802
Kg/h. in Kcal/h=Kg/h x 600
Kcal/h. in Kw/h = Kcal/h x 0.001161
Kw/h. in Hp/h = Kw/h x 1.341
Ex. Kg/h 1000 x 600 = 600,000Kcal/h
Ex. Kcal/h 600,000 x 0.001161 = 697 Kw/h
Ex. Kw/h 697 x 1.341 = 935 Hp/h
G17
a
S u n d a y
AVAL
m o r n i n g …
Inverse Process
Hp/h in Kw/h. = Hp/h x 1.341
Hp/h. in Kcal/h = Kcal/h: 0.001558
Kw/h. in Kcal/h = Kw/h: 0.001161
Ex. Hp/h 935: 1.341 = 697 Kw
Ex. Hp/h 935: 0.001558 = 600,000 Kcal/h
Ex. Kw/h 697: 0.001161 = 600,000 Kcal/h
Diagram for calculating roughly the
yield of steam generator
Increasing of gas temperature
in relation to soot thickness
fume losses in % at 13% of CO2
l i k e
fume temperature increase
®
e a s y
thickness of the soot deposit
GENERATOR’S OUTLET (TF)
Rapid calculation of fuel consumption for
steam producing boilers
Q= Quantity of fuel consumed. In Nm3/h
H = Enthalpy of steam at the corresponding pressure (Kcal/Kg steam)
TAC = Boiler feed water temperature (°C)
L.H.C = Low heat capacity of natural gas (Kcal/ Nm3/h (8000-8500)
η = Boiler yield
P = Quantity of steam produced (Kg/h)
Q=
H-TAC
xP
L.H.C x η
Example:
Boiler with 1000 Kg/h steam production
Yield η = 0.88
Steam pressure: 12 ate. Feed water temperature: 65°C.
Enthalpy or total steam heat at 12 ate = 666 Kcal/Kg
Q =
Example:
FT = 230°C AT = 30°C CO2 = 12% SHL = 10%
On finding the temperature of fumes on exit from boiler
(FT), the ambient temperature (AT) and the amount of
CO2 in the stack, the loss in percentage of sensible heat
(SHL) can be calculated by following the example given
in the diagram.
2% being taken as the percentage of the average loss of
heat for various reasons (HLP), the overall heat yield will
be calculated from:
666-16
x1000=92 Nm 3 /h
8000 x 8000 η
Example:
The same boiler as above but fed with heavy oil fuel will give:
L.H.C. = Low heat capacity of heavy oil (9800 Kcal/Kg)
Q =
Example:
The same boiler as above but fed with heavy oil fuel will give:
L.H.C. = Low heat capacity of heavy oil (9800 Kcal/Kg)
η = 100 – SHL – HLP
η = 100 – 10 – 2 = 88 (88%)
G18
666-16
x1000=70 kg/h
9800 x 0,88
Q =
666-16
x1000=68 kg/h
10000 x 0,88
®
e a s y
Diagram for calculating roughly the yield
of steam generator
Fuel heat capacity
The heat capacity is the quantity of heat expressed in
calories which is developed by burning 1 Kg of solid or
liquid fuel or 1 m3 of gaseous fuel
High heat capacity
All fuel is never completely dry, but they contain a certain
amount of water under the form of humidity; furthermore
in burning the hydrogen content more water is formed.
This water, in boiler furnaces and tubes, is steam.
If the fumes, on the exiting stack, had a temperature lower
than 100°C this steam would condense and lose the
steam calories which would be used, in this way all the
heat content in the fuel would be utilized and this would
result in high heat capacity.
Low heat capacity
If on the other hand, as happens in the boilers, the fumes
exit the stack at a temperature of over 100°C the humidity
is under the form of steam and the condensation heat is
lost in the atmosphere.
Consequently, the amount of heat which can be used is
less, therefore is we have low heat capacity.
The following page indicates the thermo-technical
characteristics of the main fuels.
FUEL
HIGH HEAT CAPACITY
LOW HEAT CAPACITY
DIESEL
10900 Kcal/Kg
10200 Kcal/Kg
FLUID OIL
10450 Kcal/Kg
9800 Kcal/Kg
NATURAL GAS
9400KCAL/Nm
3
8500 KCAL/Nm
MARKET
DEFINITION
DENSITY
at air 15°
3
26000 KCAL/Nm
characteristics
EXPLOSIVE LOW HEAT HIGH HEAT
MIXTURE CAPACITY CAPACITY
IN AIR % Kcal/Kg
Kcal/Kg
AVAL
m o r n i n g …
of
AIR
m3/m3
DEW POINT
°C
0,55
5-15
8500
9400
9,56
58
PROPANE C3H8
1,55
2,4 -9,3
22200
24000
24,3
54
BUTANE C4H10
2,09
2-7,6
29500
32000
32,3
53
LPG
1,68
2,1-9,5
24000
26000
26,3
54
PROPANED AIR
1,14
7,5-36
5900
6400
5,75
54
TOWN GAS
0,39
5-30
4200
4700
4,33
62
BIOGAS
0,89
7,8-32
5400
6000
6,12
57
Sizing diesel oil burner feed pipes
H = Difference in levels (m)
L = Length of tubes including vertical section (m)
The return tube must reach the same height as the bottom
valve otherwise there is the risk of the intake tube
becoming disconnected.
24000 KCAL/Nm
DELIVERY
DIESEL
Kg/h
from 2 from 15 from 30 from 45 from 70
to 20
to 30
to 60 to 100 to 140
Ø 10x1 Ø 12x1 Ø 12x1 Ø 14x1 Ø 16x1
Thermo-technical characteristics of liquid fuel
DENSITY
15°
S u n d a y
METHANE CH4
H (m)
MARKET
DEFINITION
a
3
3
GPL
Thermo-technical
gaseous fuel
l i k e
LOW HEAT HIGH HEAT
VISCOSITY
CAPACITY CAPACITY
at 50°C°E
Kcal/Kg
Kcal/Kg
AIR
m3/m3
PREHEAT.
FOR FUEL
OIL (KEROSENE)
0,81
/
10300
11050
11,33
NO
DIESEL
0,84
/
10200
10900
14,24
NO
HEAVY DIESEL OIL
0,87
/
/
/
/
70-80°C
LIGHT OIL 0,92
3-5
9800
10450
10,7
100-110°C
MEDIUM LIGHT OIL
0,94
5-7
/
/
/
/
HEAVY OIL HSC
(high sulfur content)
0,97
>7
9600
10200
10,5
120-140°C
HEAVY OIL LSC
(Low sulfur content)
0,97
>7
9600
10200
/
120-140°C
from 100
to 200
from 150
to 300
Ø _”
Ø _”
Ø _”
Ø _”
Lm
Lm
Lm
Lm
Lm
Lm
Lm
Lm
Lm
0
35
70
40
45
70
25
50
25
50
0,5
30
62
36
40
60
20
40
20
40
1
25
55
32
35
50
15
30
15
30
1,5
20
48
28
27
40
10
20
10
20
2
15
40
24
20
30
5
10
5
10
3
8
25
15
10
15
/
5
/
5
3,5
6
10
10
/
7
/
/
/
/
Example:
boiler with capacity of 40 Kg/h diesel. The H value is 1.5 m
and L is 20 m 12 x 1 copper tubing is chosen (with this data
the maximum acceptable measurement for L is 28 m)
G19
®
e a s y
l i k e
a
S u n d a y
AVAL
m o r n i n g …
Sizing diesel oil burner feed pipes
Example :
boiler with capacity of 65 Kg/h diesel. The H value is 1.5 m
and L is 30 m 14 x 1 copper tubing is chosen (with this data
the maximum acceptable measurement for L is 40 m)
DELIVERY
DIESEL
Kg/h
from 2 from 15 from 30 from 45 from 70
to 20
to 30
to 60 to 100 to 140
Ø 10x1 Ø 12x1 Ø 12x1 Ø 14x1 Ø 14x1
Difference in levels (m)
L = Length of tubes including vertical section (m)
The length of P should not exceed 4 m to not to overload
the sealing device of the pump.
from 150
to 200
Ø _”
Ø _”
Ø _”
Ø _”
Lm
Lm
Lm
Lm
Lm
Lm
Lm
Lm
Lm
0,5
30
90
90
60
60
20
40
20
40
1
25
80
80
50
50
15
30
15
30
1,5
20
70
70
40
40
12
25
12
25
2
15
58
58
30
30
10
20
10
20
3
8
36
36
15
15
5
10
5
10
3,5
6
25
25
7
7
/
5
/
5
H (m)
H=
from 100
to 200
Sizing heavy oil burners pipes
KCAL MAX
rendered
P
Pump
Ql/h
ØB
ØA
ØB
VISCOSITY
3-5° E
7-9° E
VISCOSITY
15-20° E
3-5° E
7-9° E
15-20° E
Fino a
400.000
300
1”
1”
1”
1”1/4
1”
1”
1”
Fino a
1.000.000
600
1”1/4
1”1/4
1”1/4
1”1/2
1”1/4
1”1/4
1”1/4
Fino a
2.000.000
600
1”1/2
1”1/4
1”1/2
1”1/2
1”1/4
1”1/4
1”1/4
Fino a
4.000.000
1000
2”
1”1/2
2”
2”
1”1/2
1”1/2
1”1/2
Fino a
6.000.000
1500
2”
2”
2”
2”1/2
1”1/2
1”1/2
1”1/2
G20
®
e a s y
NOZZLES CAPACITY
NOZZLE
CAPACITY
G.P.H.
0,85
1
1,5
1,75
2
2,25
2,5
3
4
5
6
6,50
7
PUMP PRESSURE
19 bar
20 bar
21 bar
Kg/h
Kg/h
Kg/h
4,9
5,7
8,6
10
11,5
12,9
14,3
17,2
23
28,7
34,4
37,3
40,2
5
5,9
8,8
10,3
11,8
13,2
14,7
17,7
23,5
29,4
35,3
38,3
41,2
5,1
6
9
10,6
12,1
13,6
15,1
18,1
24,1
30,2
36,2
39,2
42,2
FOR
l i k e
a
S u n d a y
AVAL
m o r n i n g …
HEAVY OIL BURNERS
NOZZLE
CAPACITY
G.P.H.
7,50
8,30
9,50
10,50
12,00
13,80
15,30
17,50
19,50
21,50
24
28
30
PUMP PRESSURE
19 bar
20 bar
Kg/h
Kg/h
43
47,6
54,5
60,2
68,9
79,2
87,8
100,4
111,9
123,4
137,7
160,7
172,1
44,1
48,9
55,9
61,8
70,6
81,2
90,1
103
114,8
126,6
141,3
164,8
176,6
21 bar
Kg/h
45,2
50,1
57,3
63,3
72,4
83,2
92,3
105,6
117,6
129,7
144,8
168,9
181
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VISCOSITY
G22
FUELS
Curve1 - diesel oil
2 - extra fluid
3 - fluid 3/5
4 - fluid 5/7
5 - heavy fuel 8
6 - heavy fuel 15-20
7 - heavy fuel viscosity 24 engler at 50°C
8 - heavy fuel viscosity 35 engler at 50°C
9 - heavy fuel viscosity 50 engler at 50°C
10 - heavy fuel viscosity 85 engler at 50°C
l i k e
a
®
S u n d a y
pumping limit
OF
e a s y
AVAL
m o r n i n g …
®
e a s y
l i k e
a
S u n d a y
AVAL
m o r n i n g …
index
TO
CONVERSION TABLE FROM TRADITIONAL
NEW INTERNATIONAL SYSTEM UNITS
pag.
4
PRESSURE / ENERGY
“
4
BASIC REFERENCES TO HEAT THEORY
“
“
“
“
“
“
“
“
“
“
5
5
6
6
6
6
8
8/9
10
10
“
“
11
11
“
“
12
12
“
“
13
13
“
“
“
“
“
14
14
14
14
14
CHARACTERISTIC ELEMENTS OF STEAM GENERATORS
CHARACTERISTICS OF STEAM BOILER’S FEED WATER PUMP
CONVERSIONS TABLES OF POWER UNITS
DIAGRAM FOR ROUGHLY CALCULATING THE YIELD OK STEAM GENERATOR
INCREASING OG GAS TEMPERATURE IN RELATION TO SOOT THICKNESS
RAPID CALCULATION OF FUEL CONSUMPTION FOR STEAM PRODUCING BOILERS
DIAGRAM FOR CALCULATING ROUGHLY THE YIELD OF STEAM GENERATOR
THERMO-TECHNICAL CHARACTERISTICS OF LIQUID FUEL
THERMO-TECHNICAL CHARACTERISTICS OF GASEOUS FUEL
SIZING DIESEL OIL BURNER FEED PIPES
SIZING HEAVY OIL BURNERS PIPES
“
“
“
“
“
“
“
“
“
“
“
“
16
16
17
17
18
18
18
19
19
19
19/20
20
VISCOSITY OF FUELS
“
22
TEMPERATURE AND HEAT
SENSIBLE HEAT
LATENT HEAT
TOTAL HEAT OF STEAM
PRODUCTION OF STEAM UNDER PRESSURE
SPACE OCCUPIED BY STEAM (SPECIFIC VOLUME)
PHYSICAL CHARACTERISTICS OF SATURATED STEAM
ENTHALPHY OF SUPERHEATED SATURATED STEAM
SPECIFIC HEAT OF SUPERHEATED STEAM
REVERSE FLAME FIRE TUBE STEAM BOILER
OPERATING PRINCIPALE
THREE PASSES WET BACK STEAM BOILER
OPERATING PRINCIPALE
TWO PASSES DRY BACK STEAM BOILER
OPERATING PRINCIPALE
WATER TUBE BOILER
OPERATING PRINCIPALE
WATER SIDE
GASSES
CONTROLLED CIRCULATION
TYPE
STEAM BOILERS GENERAL : THERMO-TECHNICAL DATA
®
e a s y
l i k e
a
S u n d a y
AVAL
m o r n i n g …
...we’ll take care of the rest.
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