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University Of Karachi
Fuel and Combustion
Heating Equipments
Syed Saad Ahmed
B-0933040
B.E 3rd
Year
Chemical Engineering
Submitted To:
Sir Saqib
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Heating Equipment
In industries we use many types of heating equipments such as follows:
Furnace Heater (electric and water) Heat pump Boiler Thermostat Humidifier Oven Stove Others
These all equipments work on different conditions such as constant temperature and
constant pressure etc. We will focus on boiler, furnace and heater from these processes
in detail.
Furnace
In furnace heat is generated at a central furnace and is then distributed and delivered to
the conditioned space via a duct system. A properly designed heating system will
generate quiet, filtered, and comfortable air into the conditioned zone.
Fuel:
There are three types of fossil fuel heating systems predominantly available on the
market today. These include natural gas, liquefied petroleum (LP) and fuel oil forced-
air furnaces. Natural gas is predominantly used as the preferred fuel. The fuel is mixed
with the air to have combustion, the amount of the air is very important for complete
combustion of the furnace, O2 is a measure of excess air and CO is a measure of the
quality of combustion. Appropriate equivalence ratio should be chosen for the better
combustion. In addition to this the initial pressure should be decreased, the initialtemperature should be increased.
Furnace at constant volume:
Constant volume systems provide each zone with a fixed airflow rate at a constant
temperature. The airflow rate is based on the design. The ducting and air handling
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system are sized to match heat from equipment. Constant volume systems can heat and
cool simultaneously.
They require some form of centralized air handling units. Most of them can use either
air or water side economizers to take advantage of free cooling during mild weather.
Since constant volume with reheat systems are simultaneous heating and cooling
systems, they are typically not energy efficient. Fan work is also very high since the fan
capacity is based on the connected load and there is no variation in air volume at part
load. Constant volume uses more fan power.
Furnace at constant pressure:
The constant pressure furnace design has been used primarily in the U.S. while the
variable pressure design has been dominant in Europe. The constant pressure furnaceutilizes tubes that are vertically oriented. The less costly vertical tube arrangement must
operate at constant pressure, utilizes multiple passes and mixes, does not permit daily
on/off cycling and exhibits a slightly higher pressure drop.
Installations of the constant pressure furnace are thermally inefficient but low fuel cost
makes them reasonably economical. Constant pressure design is high efficiency. In this
type of furnace inlet air pressure must be above the furnace pressure. Ignition of main
burners under furnace pressures up to 10 psig is smooth and stable.
Turbine
The gas turbine is an internal combustion engine that uses air as the working fluid. The
engine extracts chemical energy from fuel and converts it to mechanical energy using
the gaseous energy of the working fluid (air) to drive the engine and propeller.
Fuel:
There are regional economic and political incentives for using fuel in the gas turbine.
The power industry will need to institute design changes to accommodate these fuels.The combustion gas turbine being installed in many of todays natural gas fuelledpower plants consists of inlet section, compressor, combustion system, and turbine,exhaust system, and exhaust diffuser. Fuel enters into the combustion chambers whereit mixes with air. The amount of both fuel and air should be according to the air-fuelratio required by gas turbines.
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Turbine at constant volume:
Gas Turbines are constant volume machines. At a given shaft speed they always movethe same volume of air. But the power output of a turbine depends on the flow of mass
through it. At a constant speed, the compressor pumps a constant volume of air into theengine, if the density of the air decreases, the same volume of air will contain less mass,so less power is produced. If air density increases, power output also increases as the airmass flow increases for the same volume of air. This is precisely the reason why on hotdays, when air is less dense, power output falls off. A rise of one degree Centigradetemperature of Inlet air decreases the power output by 1% and at the same time heatrate of the turbine also goes up.
Turbine at constant pressure:As in the constant volume gas turbine if the temperature of air rises, the power output
of the Gas Turbine falls. To increase the efficiency more power is required to compresswarmer air. For this condition the following three parameters are made to be constant.
Site altitude i.e. atmospheric pressure Inlet pressure drop in the filters and intake system Outlet pressure drop in the HRSG (Heat Recovery Steam Generator)
By this we obtain a higher output and improved efficiency.
Boiler
A boiler is a closed vessel in which water or other fluid is heated. The heated orvaporized fluid exits the boiler for use in various processes or heating applications.
Mainly it is a device used to create steam by applying heat energy to water. Although
the definitions are somewhat flexible, it can be said that older steam generators were
commonly termed boilers and worked at low to medium pressure (1300psi/0.069
20.684 bar; 6.8952,068.427 kPa) but, at pressures above this, it is more usual to speak of
a steam generator. An industrial boiler originally used for supplying steam to
a stationary steam engine. A boiler or steam generator is used wherever a source of
steam is required. The form and size depends on the application: mobile steam
engines such as steam locomotives, portable engines and steam-powered road vehiclestypically use a smaller boiler that forms an integral part of the vehicle; stationary steam
engines, industrial installations and power stations will usually have a larger separate
steam generating facility connected to the point-of-use by piping.
http://en.wikipedia.org/wiki/Pressure_vesselhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Heat_energyhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Pounds_per_square_inchhttp://en.wikipedia.org/wiki/Bar_(unit)http://en.wikipedia.org/wiki/Pascal_(unit)http://en.wikipedia.org/wiki/Stationary_steam_enginehttp://en.wikipedia.org/wiki/Steam_enginehttp://en.wikipedia.org/wiki/Steam_enginehttp://en.wikipedia.org/wiki/Steam_locomotivehttp://en.wikipedia.org/wiki/Portable_enginehttp://en.wikipedia.org/wiki/Traction_enginehttp://en.wikipedia.org/wiki/Stationary_steam_enginehttp://en.wikipedia.org/wiki/Stationary_steam_enginehttp://en.wikipedia.org/wiki/Stationary_steam_enginehttp://en.wikipedia.org/wiki/Stationary_steam_enginehttp://en.wikipedia.org/wiki/Traction_enginehttp://en.wikipedia.org/wiki/Portable_enginehttp://en.wikipedia.org/wiki/Steam_locomotivehttp://en.wikipedia.org/wiki/Steam_enginehttp://en.wikipedia.org/wiki/Steam_enginehttp://en.wikipedia.org/wiki/Stationary_steam_enginehttp://en.wikipedia.org/wiki/Pascal_(unit)http://en.wikipedia.org/wiki/Bar_(unit)http://en.wikipedia.org/wiki/Pounds_per_square_inchhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Heat_energyhttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Pressure_vessel -
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Fuel:The source of heat for a boiler is combustion of any of several fuels, such
as wood, coal, oil, or natural gas. Electric steam boilers use resistance- or immersion-
type heating elements. Nuclear fission is also used as a heat source for
generating steam. Heat recovery steam generators (HRSGs) use the heat rejected from
other processes such as gas turbines.
Boiler at Constant Pressure:When the boiler is at constant pressure so for boiling we have to raise the vapor
pressure to atmospheric pressure so for doing this we have to give more amount of heat
due to raise in volume so for this heat energy is lost to change in volume.
Boiler at Constant Volume:When the boiler works at constant volume so for boiling we have to raise the
vapor pressure to the pressure built in the boiler as the volume is constant the pressure
raise and due to that temperature raises much more than boiler at constant pressure.