AT this material we'll consider water vapor, which is the gaseous state of water.
The gaseous state refers to three main aggregate states water found naturally in natural conditions. This issue is considered in detail in the material.
water vapor
Clean water vapor has no color or taste. largest cluster the pair is observed in the troposphere.
Water vapor is water contained in the atmosphere in gaseous state. The amount of water vapor in the air varies greatly; its largest content is up to 4%. Water vapor is invisible; what is called steam in everyday life (steam from breathing in cold air, steam from boiling water, etc.) is the result of the condensation of water vapor, like fog. The amount of water vapor determines the most important characteristic for the state of the atmosphere - air humidity.
Geography. Modern illustrated encyclopedia. - M.: Rosman. Under the editorship of prof. A.P. Gorkina. 2006.
How water vapor is formed
Water steam formed as a result of vaporization. Vaporization occurs as a result of two processes - evaporation or boiling. During evaporation, vapor is formed only on the surface of the substance, while boiling vapor is formed throughout the entire volume of the liquid, as evidenced by the bubbles that actively rise upward during the boiling process. Boiling water occurs at temperatures that depend on chemical composition aqueous solution and atmospheric pressure, the boiling point remains constant throughout the process. Steam, resulting from boiling, is called saturated. Saturated steam in turn is subdivided into saturated dry and saturated wet steam. Saturated wet steam consists of suspended droplets of water, the temperature of which is at the level of boiling, and, accordingly, the steam itself, and saturated dry steam does not contain water droplets.
There is also "superheated steam", which is formed by further heating of wet steam, this type of steam has a higher temperature and lower density.
Water vapor is an indispensable element of such an important process for our planet as.
We constantly encounter steam in daily life, it appears - above the spout of the kettle when boiling water, when ironing, when visiting a bath ... However, do not forget that, as we noted above, clean water vapor has no color or taste. Thanks to their physical properties and qualities, steam has long since found its practical use in economic activity person. And not only in everyday life, but also in solving large global problems. For a long time steam was the main driving force progress both directly and figuratively this expression. It was used as the working body of steam engines, the most famous of which is the steam locomotive.
Use of steam by man
Steam is still widely used in household and industrial needs:
- for hygiene purposes;
- for medicinal purposes;
- to extinguish fires;
- the thermal properties of steam are used (steam as a heat carrier) - steam boilers; steam jackets (autoclaves and reactors); heating of "freezing" materials; heat exchangers; heating systems; steaming of concrete products; in a special kind of heat exchangers ...;
- use the transformation of steam energy into motion - steam engines … ;
- sterilization and disinfection - food industry, Agriculture, the medicine … ;
- steam as a humidifier - in the production of reinforced concrete products; plywood; in Food Industry; in the chemical and perfume industries; in woodworking industries; in agricultural production ...;
Summing up, we note that, despite all its "invisibility", water vapor is not only important element global eco-system of the Earth, but also very useful substance for business and economic activity person.
Topic 2. Fundamentals of heat engineering.
Heat engineering is a science that studies the methods of obtaining, transforming, transferring and using heat. Thermal energy is obtained by burning organic matter called fuel.
The basics of heat engineering are:
1. Thermodynamics - a science that studies the conversion of heat energy into other types of energy (for example: thermal energy into mechanical, chemical, etc.)
2. Heat transfer - studies heat transfer between two heat carriers through a heating surface.
The working fluid is a coolant (steam or hot water), which is capable of transferring heat.
In the boiler room, the heat carrier (working fluid) is hot water and water vapor with a temperature of 150 ° C or water vapor With temperatures up to 250°C. Hot water is used for heating residential and public buildings, this is due to sanitary and hygienic conditions, the possibility easy change its temperature depending on the outside temperature. Water has a significant density compared to steam, which allows you to transfer to long distances a significant amount of heat with a small volume of coolant. Water is supplied to the heating system of buildings at a temperature not exceeding 95 ° C in order to avoid burning dust on heating devices and burns from heating systems. Steam is used for heating industrial buildings and in industrial and technological systems.
Working body parameters
The coolant, receiving or giving thermal energy, changes its state.
For example: Water in a steam boiler heats up, turns into steam, which has a certain temperature and pressure. The steam enters the steam-water heater, cools itself, and turns into condensate. The temperature of the heated water increases, the temperature of the steam and condensate decreases.
The main parameters of the working fluid are temperature, pressure, specific volume, density.
t, P- is determined by instruments: pressure gauges, thermometers.
Specific volume and density is a calculated value.
1. Specific volume- the volume occupied by a unit mass of a substance at
0°С and atmospheric pressure 760 mm Hg. (at normal conditions)
where: V- volume (m 3); m is the mass of the substance (kg); standard condition: R=760mm R.st. t=20 o C
2. Density is the ratio of the mass of a substance to its volume. 
each substance has its own density:
In practice, it is applied relative density is the ratio of the density of a given gas to the density standard substance(air) under normal conditions (t° = 0°С: 760 mm Hg)
By comparing the density of air with the density of methane, we can determine where to sample for methane.
we get
gas is lighter than air, so it fills upper part of any volume, the sample is taken from the upper part of the boiler furnace, well, chambers, premises. Gas analyzers are installed in the upper part of the premises.
(fuel oil is lighter, occupies the upper part)
The density of carbon monoxide is almost the same as that of air, so the sample carbon monoxide taken 1.5 meters from the floor.
3. Pressure is the force acting per unit area of the surface.
Pressure force equal to 1 H, uniformly distributed on the surface of 1m 2 is taken as a unit of pressure and is equal to 1Pa (N/m2) in the SI system (now in schools, in books everything goes to Pa, devices also became in Pa).
The value of Pa is small in value, for example: if we take 1 kg of water and pour it into 1 meter, we get 1 mm.w.st. , therefore, multipliers and prefixes are introduced - MPa, KPa ...
In technology, more than large units measurements
1kPa \u003d 10 3 Pa; 1MPa=10 b Pa; 1GPa=10 9 Pa.
Outside Pressure Units kgf / m 2; kgf / cm 2; mm.v.st; mm.r.st.
1 kgf / m 2 = 1 mm.v st \u003d 9.8 Pa
1 kgf / cm 2 = 9.8. 10 4 Pa ~ 10 5 Pa = 10 4 kgf / m 2
Pressure is often measured in physical and technical atmospheres.
physical atmosphere - average pressure atmospheric air at sea level at n.o.s.
1atm = 1.01325. 10 5 Pa = 760 mm Hg = 10.33 m aq. st \u003d 1.0330 mm in. Art. \u003d 1.033 kgf / cm 2.
Technical atmosphere- pressure caused by a force of 1 kgf is evenly distributed over a surface normal to it with an area of 1 cm 2.
1 at \u003d 735 mm Hg. Art. = 10 m.v. Art. = 10.000 mm in. Art. \u003d \u003d 0.1 MPa \u003d 1 kgf / cm 2
1 mm in. Art. - a force equal to hydrostatic pressure 1 column of water mm on a flat base 1 mm in. st \u003d 9.8 Pa.
1 mm. rt. st - a force equal to the hydrostatic pressure of a column of mercury with a height of 1 mm on a flat base. one mm rt. Art. = 13.6 mm. in. Art.
AT technical specifications pumps instead of pressure, the term pressure is used. The unit of pressure is m. of water. Art. For example: The pressure created by the pump is 50 m water. Art. which means he can lift water to a height of 50 m.
Types of pressure: excess, vacuum (vacuum, thrust), absolute, atmospheric .
If the arrow deviates to the side greater than zero, then this is excess pressure, to the lower side - vacuum.
Absolute pressure:
R abs \u003d R ho + R atm
R abs \u003d R vac + R atm
R abs \u003d R atm -R razr
where: R atm \u003d 1 kgf / cm 2
Atmosphere pressure - average pressure of atmospheric air at sea level at t° = 0°C and normal atmospheric R=760 mm. rt. Art.
Overpressure- pressure above atmospheric (in a closed volume). In boiler houses, water, steam in boilers and pipelines are under excess pressure. R izb. measured with manometers.
Vacuum (Vacuum)- pressure in closed volumes is less than atmospheric pressure (vacuum). The furnaces and chimneys of the boilers are under vacuum. Vacuum is measured by draft gauges.
Absolute pressure- excess pressure or rarefaction, taking into account atmospheric pressure.
By appointment, the pressure is:
one). Channel - the highest pressure at t=20 o C
2). Working - the maximum excess pressure in the boiler, which ensures long-term operation of the boiler under normal operating conditions (indicated in the production instructions).
3). Allowed - the maximum allowable pressure, established by the results of a technical examination or a control calculation for strength.
four). Calculated - the maximum overpressure at which the strength of the boiler elements is calculated.
5). R test - overpressure at which hydraulic tests of boiler elements are carried out for strength and density (one of the types of technical examination).
4. Temperature- this is the degree of heating of the body, measured in degrees. Determines the direction of spontaneous heat transfer from a hotter to a cooler body.
Heat transfer will take place until the temperatures become equal, i.e., temperature equilibrium occurs.
Two scales are used: international - Kelvin and practical Celsius t ° С.
Zero in this scale is the melting point of ice, and one hundred degrees is the boiling point of water at atm. pressure (760 mm rt. Art.).
For the reference point in the Kelvin thermodynamic temperature scale, apply absolute zero(lower theoretically possible temperature, at which there is no movement of molecules). Denoted T.
1 Kelvin is equal in magnitude to 1° Celsius
The melting temperature of ice is 273K. The boiling point of water is 373K
T=t+273; t=T-273
The boiling point depends on pressure.
For example, At R ab c \u003d 1,7 kgf / cm 2. Water boils at t = 115°C.
5. Warmth - energy that can be transferred from a hotter body to a cooler one.
The SI unit for heat and energy is the Joule (J). The off-system unit of heat is the calorie ( cal.).
1 cal.- the amount of heat required to heat 1 g of H 2 O by 1 ° C at
P = 760 mm. Hg
1 cal.=4.19J
6.Heat capacity – body's ability to absorb heat . In order for two various substances with the same mass to heat to the same temperature, you need to spend different quantity warmth.
The specific heat capacity of water - the amount of heat that must be reported by a unit of a substance in order to increase its t by 1 ° C, is equal to 1 kcal/kg deg.
Heat transfer methods.
There are three types of heat transfer:
1.thermal conductivity;
2.radiation (radiation);
3.convection.
Thermal conductivity-
Heat transfer due to thermal motion of molecules, atoms and free electrons.
Each substance has its own thermal conductivity, it depends on the chemical composition, structure, moisture content of the material.
Quantitative characteristic thermal conductivity is the coefficient of thermal conductivity is the amount of heat transferred through a unit of heating surface per unit time with a difference t in o C and a wall thickness of 1 meter.
Coefficient of thermal conductivity ( ):
Copper = 330 kcal . mm 2. h . hail
Cast iron = 5 4 kcal . mm 2. h . hail
Steel =39 kcal . mm 2. h . hail
It can be seen that: metals have good thermal conductivity, copper is best.
Asbestos \u003d 0.15 kcal . mm 2. h . hail
Soot \u003d 0.05-0, kcal . mm 2. h . hail
Scale \u003d 0.07-2 kcal . mm 2. h . hail
Air =0.02 kcal . mm 2. h . hail
Poorly conduct heat porous bodies (asbestos, soot, scale).
Soot hinders the transfer of heat from flue gases to the boiler wall (conducts heat 100 times worse than steel), which leads to excessive fuel consumption, reduced steam production or hot water. In the presence of soot, the temperature of the flue gases rises. All this leads to a decrease in the efficiency of the boiler. During boiler operation hourly according to instruments (logometer) t flue gases are controlled, the values \u200b\u200bof which are indicated in regime map boiler. If t flue gas has increased, then the heating surface is blown.
Scale is formed inside the pipes (it conducts heat 30-50 times worse than steel), thereby reducing heat transfer from the boiler wall to water, as a result, the walls overheat, deform, and burst (rupture of the boiler pipes). Scale conducts heat 30-50 times worse than steel
Convection -
Heat transfer by mixing or moving particles between themselves (characteristic only for liquids and gases). Distinguish between natural and forced convection.
natural convection - free movement liquids or gases due to the difference in densities of unevenly heated layers.
forced convection- forced movement of liquid or gases due to pressure or vacuum created by pumps, smoke exhausters and fans.
Enlargement methods convective heat transfer:
§ Increasing the flow rate;
§ Turbulization (swirl);
§ Increasing the heating surface (due to the installation of fins);
§ Increasing the temperature difference between the heating and heated media;
§ Countercurrent movement of media (countercurrent).
Emission (radiation) -
Heat exchange between bodies located at a distance from each other due to radiant energy, the carriers of which are electromagnetic oscillations: there is a transformation of thermal energy into radiant and vice versa, from radiant to thermal.
Radiation most effective method heat transfer, especially if the studying body has high temperature, and the rays are directed perpendicular to the heated surface.
To improve heat transfer by radiation in the furnaces of boilers, special slots are laid out of refractory materials, which are both heat emitters and combustion stabilizers.
The heating surface of the boiler is a surface from which, on the one hand, it is washed by gases, and on the other hand, by water.
Discussed above 3 types of heat exchange in pure form are rare. Almost one type of heat transfer is accompanied by another. All three types of heat transfer are present in the boiler, which is called complex heat transfer.
In the boiler furnace:
A) from the burner flame to the outer surface of the boiler pipes - by radiation.
B) from the resulting flue gases to the wall - convection
C) from the outer surface of the pipe wall to the inner - thermal conductivity.
D) from inner surface pipe walls to water, circulation along the surface - convection.
The transfer of heat from one medium to another through a separating wall is called heat transfer.
Water, water vapor and its properties
Water is the simplest stable in normal conditions chemical compound hydrogen with oxygen highest density water 1000kg / m 3 at t \u003d 4 ° C.
Water, like any liquid, is subject to hydraulic laws. It almost does not shrink, therefore it has the ability to transfer the pressure exerted on it in all directions with the same force. If several vessels different shapes connect with each other, then the water level will be the same everywhere (the law of communicating vessels).
Similar information.
water vapor - working fluid in steam turbines, steam engines, nuclear power plants, coolant in various heat exchangers.
Steam - gaseous body in a state close to boiling liquid.
vaporization - the process of converting a substance from liquid state into vapor.
Evaporation - vaporization, which always occurs at any temperature from the surface of the liquid.
At a certain temperature, depending on the nature of the liquid and the pressure under which it is located, vaporization occurs in the entire mass of the liquid. This process is called boiling .
The reverse process of vaporization is called condensation . Condensation, like vaporization, proceeds at a constant temperature.
The process by which a solid changes directly into vapor is called sublimation . Reverse process of steam transition to solid state called desublimation .
When liquid evaporates into confined space(in steam boilers) the opposite phenomenon occurs at the same time - steam condensation. If the rate of condensation becomes equal speed evaporation, then dynamic equilibrium occurs. The vapor in this case has a maximum density and is called rich ferry .
If the steam temperature is higher than the temperature of saturated steam of the same pressure, then such steam is called overheated .
The difference between the temperature of superheated steam and the temperature of saturated steam at the same pressure is called degree of overheating .
Since the specific volume of superheated steam is greater than the specific volume of saturated steam, the density of superheated steam is less than the density of saturated steam. Therefore, superheated steam is unsaturated.
At the moment of evaporation of the last drop of liquid in a limited space without changing temperature and pressure (that is, when the liquid stops evaporating), dry saturated steam . The state of such steam is determined by one parameter - pressure.
The mechanical mixture of dry and tiny droplets of liquid is called wet ferry .
Mass fraction of dry steam in wet steam - degree of dryness X:
x=m cn /m vp , (6.7)
where m cn- mass of dry steam in wet; m vp is the mass of wet steam.
Mass fraction at liquids in wet steam - degree humidity :
at= 1–x = 1–m cn /m vp = (m vp –m cn)/m vp . (6.8)
6.4. Moist Air Characteristics
Atmospheric air, mainly consisting of oxygen, nitrogen, carbon dioxide, always contains some water vapor.
A mixture of dry air and water vapor is called wet air . Humid air at a given pressure and temperature can contain varying amounts of water vapor.
A mixture of dry air and saturated water vapor is called saturated wet air . In this case, the maximum possible amount of water vapor for a given temperature is in moist air. As this air cools, water vapor will condense. The partial pressure of water vapor in this mixture is equal to the saturation pressure at a given temperature.
If moist air contains water vapor in a superheated state at a given temperature, then it is called unsaturated . Since it does not contain the maximum possible amount of water vapor for a given temperature, it is capable of further moistening. This air is used as drying agent in various dryers.
According to Dalton's law, pressure R moist air is the sum of the partial pressures of dry air R in and water vapor R P :
p = p in + p P . (6.9)
Maximum value p P at a given temperature of humid air is the pressure of saturated water vapor p n .
To find the partial pressure of a vapor, use special device - hygrometer . This device is used to determine dew point , that is, the temperature t p to which air must be cooled at constant pressure to become saturated.
Knowing the dew point, it is possible to determine the partial pressure of vapor in air from the tables as saturation pressure p n corresponding to the dew point t p .
Absolute humidity air is called the amount of water vapor in 1 m 3 of moist air. Absolute humidity is equal to the density of vapor at its partial pressure and air temperature t n .
The ratio of the absolute humidity of unsaturated air at a given temperature to the absolute humidity of saturated air at the same temperature is called relative humidity air
φ=s P /With n or φ= (With P /With n) 100%, (6.10)
For dry air φ =0, for unsaturated φ <1, для насыщенного φ =1 (100%).
Considering water vapor as an ideal gas, according to the Boyle-Mariotte law, the ratio of densities can be replaced by the ratio of pressures. Then:
φ=ρ P /ρ n or φ= p P / p n·100%. (6.11)
The density of moist air is made up of the masses of dry air and water vapor contained in 1 m 3 of volume:
ρ=ρ in +ρ P = p in / (R in T)+φ/ v′′ . (6.12)
The molecular weight of moist air is determined by the formula:
μ =28,95–10,934φ∙ p n / p . (6.13)
Values p n and v′′ at air temperature t taken from the water vapor table, φ - according to the psychrometer, p- by barometer.
Moisture content is the ratio of the mass of steam to the mass of dry air:
d=M P /M in , (6.14)
where M P , M in- masses of steam and dry air in moist air.
Relationship between moisture content and relative humidity:
d=0,622φ· p n ·/( p - φ· p n). (6.15)
Air gas constant:
R=8314/μ =8314/(28.95–10.934 μ· p n / p). (6.16)
The following formula is also valid:
R = (287+462d)/(1+d).
The volume of moist air per 1 kg of dry air:
V ow.v = R T/p. (6.17)
Specific volume of moist air:
v=V ow.v /(1+d). (6.17a)
Specific mass heat capacity of the steam-air mixture:
With cm = with in +d s P . (6.18)
For the nature around us, water vapor is of great importance. It is present in the atmosphere, is used in technology, and serves as an integral part of the process of the origin and development of life on Earth.
Physics textbooks say that water vapor is what everyone can observe by putting a kettle on fire. After a while, a jet of steam begins to escape from its spout. This phenomenon is due to the fact that water can be in different, as physicists define, states of aggregation - gaseous, solid, liquid. Such properties of water explain its all-encompassing presence on Earth. On the surface - in a liquid and solid state, in the atmosphere - in a gaseous state.
This property of water and its successive transition to different states are created in nature. The liquid evaporates from the surface, rises into the atmosphere, is transported to another place in the form of water vapor and falls there as rain, providing the necessary moisture to new places.
In fact, a kind of steam engine is operating, the source of energy for which is the Sun. In the processes considered, water vapor additionally heats the planet due to its reflection of the Earth's thermal radiation back to the surface, causing the greenhouse effect. If it were not for such a kind of "cushion", then the temperature on the surface of the planet would be 20 ° C lower.
As confirmation of the above, we can recall the sunny days in winter and summer. In the warm season, it is high, and the atmosphere, like in a greenhouse, warms the Earth, while in winter, in sunny weather, sometimes the most significant colds occur.
Like all gases, water vapor has certain properties. One of the parameters that determine these will be the density of water vapor. By definition, this is the amount of water vapor contained in one cubic meter of air. In fact, this is how the latter is defined.
The amount of water in the air is constantly changing. It depends on temperature, pressure, terrain. The moisture content in the atmosphere is an extremely important parameter for life, and it is constantly monitored, for which special devices are used - a hygrometer and a psychrometer.
The change in humidity is caused by the fact that the water content in the surrounding space changes due to the processes of evaporation and condensation. Condensation is the opposite of evaporation, in this case, the vapor begins to turn into a liquid, and it falls to the surface.
In this case, depending on the ambient temperature, fog, dew, frost, ice may form.
When warm air, water, comes into contact with cold earth, dew forms. In winter, at low temperatures, frost will form.
A slightly different effect occurs when cold air comes in, or air heated during the day begins to cool. In this case, fog is formed.
If the temperature of the surface on which the steam condenses is negative, then ice occurs.
Thus, numerous natural phenomena, such as fog, dew, hoarfrost, ice, owe their formation to the water vapor contained in the atmosphere.
In this regard, it is worth mentioning the formation of clouds, which are also most directly involved in the formation of weather. Water, evaporating from the surface and turning into water vapor, rises up. Upon reaching the height where condensation begins, it turns into a liquid, and clouds form. They can be of several types, but in the light of the issue at hand, it is important that they are involved in creating a greenhouse effect and transporting moisture to new places.
The presented material shows what water vapor is, describes its effect on life processes occurring on Earth.
Water vapor is produced in steam boilers at constant pressure and constant temperature. First, the water is heated to boiling point (it remains constant) or saturation temperature. . With further heating, boiling water turns into steam and its temperature remains constant until the water completely evaporates. Boiling is the process of vaporization in the entire volume of a liquid. Evaporation - vaporization from the surface of the liquid.
The transition of a substance from a liquid state to a gaseous state is called vaporization , and from a gaseous state to a liquid condensation . The amount of heat that must be imparted to water in order to change it from a liquid state to a vapor state at its boiling point is called heat of evaporation .
Amount of heat required for heating 1 kg water per 1 0 C is called heat capacity of water . = 1 kcal/kg. deg.
The boiling point of water depends on pressure (there are special tables):
R abs = 1 kgf / cm 2 = 1 atm, t k \u003d 100 ° С
R abs = 1.7 kgf / cm 2, t k \u003d 115 ° С
R abs = 5 kgf / cm 2, t k \u003d 151 ° С
R abs =10 kgf / cm 2, t k = 179°С
R abs = 14 kgf / cm 2, t k = 195°С
At a water temperature in boiler rooms at the outlet of 150 ° C and return t in-
at 70°C each kg of water carries 80 kcal warmth.
In steam supply systems 1 kg water steamed portable approx. 600 kcal warmth.
Water is practically incompressible. Takes up the smallest volume t=+4°С. At t above and below +4°C, the volume of water increases. The temperature at which condensation of excess water vapor begins is called t "dew point".
Distinguish steam saturated and overheated. During evaporation, some of the molecules fly off the surface of the liquid and form vapor above it. If the temperature of the liquid is kept constant, i.e., heat is continuously supplied to it, then the number of ejected molecules will increase, while due to the chaotic movement of the vapor molecules, simultaneously with the formation of vapor, the reverse process occurs - condensation in which part of the vapor molecules returns to the liquid .
If evaporation occurs in a closed vessel, then the amount of vapor will increase until equilibrium is reached, i.e., the amount of liquid and vapor becomes constant.
A vapor that is in dynamic equilibrium with its liquid and has the same temperature and pressure with it is called saturated steam.
Wet saturated steam, called steam, in which there are droplets of boiler water; saturated steam without water droplets is called dry saturated steam .
The proportion of dry saturated steam in wet steam is called the degree of steam dryness (x). In this case, the moisture content of the steam will be equal to 1 - X. For dry saturated steam x = 1. If heat is imparted to dry saturated steam at constant pressure, then superheated steam is obtained. The superheated steam temperature is higher than the boiler water temperature. Superheated steam is obtained from dry saturated steam in superheaters, which are installed in the boiler flues.
The use of wet saturated steam is not desirable, because when it moves through steam pipelines, hydraulic shocks (sharp shocks inside the pipes) of condensate that accumulate in fittings, on curves and in low places in steam pipelines, as well as in steam pumps, are possible. A sharp drop in pressure in a steam boiler to atmospheric pressure is very dangerous, which can occur as a result of an emergency violation of the strength of the boiler, since the water temperature before such a change in pressure was above 100 ° C, then the excess heat is spent on vaporization, which occurs almost instantly. The amount of steam rises sharply, which leads to an instant increase in pressure in the boiler and to serious damage. The larger the volume of water in the boiler and the higher its temperature, the greater the consequences of such destruction. The volume of steam is 1700 times the volume of water.
Superheated steam - steam having a higher temperature than saturated steam at the same pressure - does not have moisture. Superheated steam is produced in a special superheater, where dry saturated steam is heated by flue gases. Superheated steam is not used in heating boiler rooms, so there is no superheater.
Main properties of saturated steam:
1) t sat. steam = t kip. water at a given R
2) t b.p. water depends on Rsteam in the boiler
3) saturated steam condenses.
The main properties of superheated steam:
1) superheated steam does not condense
2) t superheated steam does not depend on the steam pressure in the boiler.
(Scheme for obtaining steam in a steam boiler) (cards on page 28 are optional)
