Heating equipments

8/2/2019 Heating equipments

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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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Fuel and Combustion 2012

2 Prepared By: Syed Saad Ahmed | B.E Chemical Engineering

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.

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Heating equipments