Intro To Boilers

Front 1

Baffle

Back 1

A wall, barrier, or panel used to change the direction of flow of a liquid or gas. On the waterside of a boiler, baffles may be used to direct the flow of water inside drums or headers. On the fireside of the boiler, baffles may be used to redirect the flow of hot combustion gases through banks of tubes. Fireside baffles are usually made of high temperature refractory material.

Front 2

Blowdown Valves

Back 2

Located on the line leading from the lowest part of the waterside of the boiler. Power (high-pressure) boilers usually require a fast opening (guard valve) and slow opening valve. Heating (low-pressure) boilers usually only require one blowdown valve.

Front 3

Boiler Failure

Back 3

Occurs when a ruptured or cracked tube allows high-pressure steam or water to escape, requiring the boiler to shut down. Usually applies to the pressurized parts of the boiler. Catastrophic boiler failure is observed when a combustion explosion, or rapid pressure release from the water side of the boiler, causes further destruction of the boiler and may cause damage to surrounding buildings, equipment or personnel.

Front 4

Combustion Chamber

Back 4

Where air and fuel combine in a chain reaction to cause sustained burning. Also called furnace or firebox.

Front 5

Combustion Gases

Back 5

Hot gases from the fire. Also called flue gases.

Front 6

Combustion Gas Pass

Back 6

The path that the combustion gases travel along the length of the boiler. If the gases are reversed and passed through the boiler again, this is a second pass.

Front 7

Condensate

Back 7

When steam from a boiler is used for heating, processing, or power generation, heat energy is given up to the process and the steam condenses. The water formed from condensing steam is called condensate. Condensate is usually returned to the boiler to be converted to steam again.

Front 8

Drum

Back 8

The boiler shell, together with the heads, form a drum to contain the fluid being heated. The term shell and drum are often used interchangeably. Shell may be more common in terms of firetube biolers, where drum is more often used for watertube boilers.

Front 9

Externally-Fired Boiler

Back 9

A boiler with the combustion chamber outside of the boiler shell. This type of furnace is not surrounded by water but is surrounded by brickwork.

Front 10

Feedwater

Back 10

The water that is fed into a steam boiler to replace the water which has been converted to steam and drawn off from the boiler. Usually includes the condensate.

Front 11

Fitting

Back 11

Any valve, gauge, regulating or controlling device, flange, pipe fitting or other attachment on the boiler.

Front 12

Flame Scanner

Back 12

A device used to monitor the flame in a boiler. If the flame is extinguished for any reason, the scanner may send a signal to close the fuel supply valve to prevent a possible explosion.

Front 13

Flue Gases

Back 13

Hot gaseous products from the fire.

Front 14

Forced Draft Fan

Back 14

Supplies air to the furnace for the combustion process.

Front 15

Gauge Glass

Back 15

A strong tubular glass used to indicate the water level in a steam boiler. Some high pressure boilers use heavy flat glass sections firmly clamped to a hollow metal frame, or circular glass "bullseyes" arranged in a vertical column.

Front 16

Generally Supervised Boiler

Back 16

One that can operate without continual control by an operator. The boiler may operate overnight or on weekends without an operator present. However through the week someone may occasionally check the boiler and verify that:

- All controls are working

- The boiler water is correctly treated

- The boiler is working properly

Also known as an automatic or protected boiler

Front 17

Handhole

Back 17

A small, hand-sized inspection, cleaning, and maintenance port leading from the outside of the boiler into the pressure area of the boiler. A handhole cover seals the port during operation.

Front 18

Header

Back 18

A large pipe which supplies to, or collects from, a series of smaller pipes or tubes. Also called a manifold.

Front 19

Heads

Back 19

The steel plates which close off the ends of the boiler drum. Also called end plates. If the shell contains tubes which are held in position by the heads, then they are usually called tube sheets.

Front 20

Heating Surface

Back 20

Includes all parts of the boiler through which heat from the burning fuel is transferred to the waterside of the boiler. It includes all parts of the boiler plates and tubes which have water or steam on one side and are swept by fire or hot combustion gases on the other side.

Front 21

High-Pressure Steam Boiler

Back 21

One which operates at pressures above 103 kPa. Also called power boilers.

Front 22

Horizontal Return Tubular Boiler (HRT)

Back 22

A firetube boiler usually supported in a brick combustion chamber. The hot gases from combustion sweep along the underside of the shell then return through the firetubes to the chimney connection.

Front 23

Hot Water Boiler

Back 23

A closed vessel completely filled with water to which heat is added to raise the temperature of the water. No steam is generated in this boiler. Types include:

- Low-pressure hot water heating boilers

- Hot water supply boilers (aka water heaters or hot water tanks)

- High temperature hot water boilers

Not considered heating boilers unless one of the following is exceeded:

- Capacity - 450 L

- Temperature - 99oC

- Energy Input - 58.7 kW

When above 121oC and/or 1100 kPa, called high temperature water boilers and treated like high pressure steam boilers.

Front 24

Induced Draft Fan

Back 24

Draws combustion gases out of the boiler and discharges them up the chimney.

Front 25

Internally-Fired Boiler

Back 25

Has the combustion chamber located within the shell of the boiler, or a furnace surrounded by watertubes.

Front 26

Limit Controls

Back 26

The controls that have their set point adjusted higher than the boiler operating controls set point. If, for any reason, the normal operating controls fail to limit the rise in temperature or pressure to a safe value, the limit controls will shut off the boiler fuel supply.

Front 27

Lowest Permissible Water Level

Back 27

The lowest level at which the boiler can be safely operated without damaging or overheating any part of the boiler.

Heating boilers - specified by manufacturer. Lowest visible part of the water gauge glass is 25 mm above the lowest permissible water level.

Power boilers - lowest visible part of the gauge glass is 50 mm above this lowest permissible water level.

HRT boilers - lowest visible part of the gauge glass is set not less than 76 mm above the highest point of the tubes, flue, or crown sheet.

Front 28

Low- Pressure Steam Boiler

Back 28

A boiler which operates at a pressure not above 103 kPa. Aka Heating boilers.

Front 29

Low-Water Fuel Cutoff

Back 29

A safety device which cuts off the fuel supply to the burner if the boiler water level drops below a safe level.

Front 30

Manhole

Back 30

An opening or hatch through which a person may enter into the shell or drum of a boiler.

Front 31

Operating Controls

Back 31

The controls which operate the combustion and feedwater equipment on a boiler. Changes in steam demand from the boiler require a corresponding change in the boiler firing rate and feedwater flow rate.

Front 32

Packaged Boiler

Back 32

A boiler supplied by the manufacturer completely equipped and mounted on its own base.

Front 33

Pressure Gauge

Back 33

A fitting attached to a boiler to indicate the internal pressure of the boiler. All steam boilers must be equipped with an accurate pressure gauge. Aka steam gauge.

Front 34

Refractory

Back 34

A protective layer of material that is applied to various parts of the boiler to withstand high temperatures and abrasion. It usually has an appearance similar to cement or bricks.

Front 35

Rupture Disk

Back 35

A safety device which acts like a safety valve to protect against excessive pressure build-up in a system. However, the disk ruptures when its maximum pressure is reached and must be replaced each time it activates.

Front 36

Safety Valve

Back 36

A fitting that prevents the pressure within a steam boiler from exceeding safe limits. WHen the pressure inside the boiler reaches a set point, the valve will pop open and reduce the pressure to another preset point and then close.

Safety valves are used where liquids are present. This type of valve does not "pop" open but only bleeds off enough liquid to relieve the excess pressure.

Front 37

Setting

Back 37

The brickwork used to support a boiler and surround the combustion chamber. Particularly used for such boilers as a horizontal return tubular boiler (HRT).

Front 38

Sootblower

Back 38

A device used to blow accumulated soot off tubes and heating surfaces in a boiler. Air or steam issues from nozzles to dislodge the soot or flyash as the sootblower traverses or is rotated to clear the deposit from a section of the boiler.

Front 39

Stack

Back 39

The hollow duct through which combustion gases are elevated for discharge to the atmosphere. The hot combustion gases, rising through the stack, cause a draft to be created in the boiler. May also be called a smoke stack or chimney.

Front 40

Steam Drum

Back 40

A closed container partially filled with water. The water is evaporated to steam under pressure by the application of heat. The steam is piped away for specific purposes.

Front 41

Steam Space

Back 41

The space above the water line in a steam boiler where the boiling water and steam can separate from each other. The space also acts as a pressure reservoir to accommodate small load fluctuations.

Front 42

Steam Stop Valve

Back 42

The main valve on the steam line leaving the boiler. Must be able to positively halt the flow of steam.

Front 43

Uptake

Back 43

The duct used to convey the spent combustion gases from the boiler to the stack or chimney. Aka flue, vent, or breeching.

Front 44

Vertical Tubular Boiler

Back 44

A smaller sized firetube boiler with vertical firetubes. Some hot water supply boilers are of the vertical tubular type.

Front 45

Water Column

Back 45

A chamber attached to the top and bottom of a boiler's steam drum, The water level in the column should be the same as in the boiler. A gauge glass is normally attached to the column to give a visual indication of the water level.

Front 46

Water Line

Back 46

The actual level of the boiler which is normally filled with water.

Front 47

Water Space

Back 47

The portion of the boiler which is normally filled with water.

Front 48

Waterleg

Back 48

A water-filled section extending from the shell, which surrounds the firebox of some types of firetube boilers. Most locomotive boilers are equipped with waterlegs around the firebox.

Front 49

Watertube Boiler

Back 49

A boiler consisting of drums and headers that circulate water through tubes which are heated by fire and the products of combustion. The heat from the fire is transmitted through the tubes to the water.

Front 50

Windbox

Back 50

The box surrounding the burner damper on a boiler. The forced draft fan blows combustion air into the box and the damper regulates and directs the air into the burners.

Front 51

GENERAL REQUIREMENTS FOR PROPER BOILER DESIGN

Back 51

1. It must have a large heating surface so that the maximum amount of heat
can be absorbed.
2. All parts of the boiler heating surface exposed to fire or hot gases must be
covered by water.
3. It must have a thorough circulation of water through all parts of the boiler
in order to prevent overheating of any part of the heating surface.
4. The boiler must be properly insulated to minimize heat loss to the
surroundings.
5. The steam space must be large and the steam able to rise freely from the
surface of the water, so that any water contained in the steam may be
separated before the steam is drawn off from the boiler.
6. All parts of the boiler must be readily accessible for inspection, cleaning,
and repairs.
7. It must incorporate proper workmanship, simple construction, and low
maintenance costs.
8. It must have strong enough construction according to code for pressures
and temperatures encountered.
9. It must have proper allowance for expansion and contraction of the boiler
and its parts.
10. It must be furnished with the approved fittings such as gages, safety
valves, etc.

Front 52

Specific use of high pressure, temperature and capacity boilers

Back 52

Producing electrical power

Front 53

Specific use of thermo flooding boilers

Back 53

Inject large amounts of heat energy into geological formations

Front 54

Specific use of firetube, watertube and cast-iron sectional boilers in buildings

Back 54

Heating and cooling systems