2Nd Class Fireman, High Pressure Boilers, Chapter 5, Notecards

Front 1

Blowdown

Back 1

- The process of opening valves to blow water or steam through a fitting or from a boiler in order to remove any sludge, sediment, or other undesirable particles

- to control high water

- to control chemical concentration

- to drain the boiler for cleaning and inspection

Front 2

Centrifugal Feedwater Pump

Back 2

https://m.youtube.com/watch?v=BaEHVpKc-1Q

https://m.youtube.com/watch?v=lmjIQqo8mX4

- A pump that uses the centrifugal force of a rotating element to pressurize water so it can be added to a boiler

- the basic parts are the: casing, impeller, impeller shaft, shaft bearings, and packing glands or mechanical seals.

- a discharge valve on this device cannot be opened until the pump is started.

- high velocity, you need to prime it.

- pressure gauges are on this pump

- it is one of the rotary pumps which uses kinetic energy for the impeller

- it continuously discharges the fluid

- in centrifugal pump the flow rate decreases which increases the pressure.

- it is used for pumping high viscous fluid.

- This pumps discharge is inversely proportional to the viscosity of fluid.

- efficiency of this pump is low compared to reciprocating pump.

- centrifugal pumps have problems with priming

- it uses impellers to transfer energy to fluid.

- they are lighter than reciprocating pumps.

- it gives higher discharge at low heads.

- it is less costly.

- these pumps require less maintenance.

Front 3

Closed Feedwater Heater

Back 3

- A shell-and-tube feedwater heater used to capture heat from continuous blowdown water from a boiler or flash steam from a process.

- steam and feedwater do not mix in this heater.

- equipped with a safety valve on the steam side and a relief valve in the feedwater side.

- located on the discharge side of the feedwater pump and therefore applies a higher pressure on the feedwater than the open feedwater heater.

- used to reduce thermal shock on the boiler metal and it also increases plant efficiency.

- the heat in the steam is transferred to the water to raise the water temperature

- the steam that condenses back into water is removed with a steam trap.

Front 4

Deaerator

Back 4

- A feedwater heater operating under pressure used to separate oxygen and other gases from the steam before releasing the gases to the atmosphere through a vent

- typically use steam to heat water

-used to hold and preheat boiler feedwater before it is pumped into the boiler. This increases the sensible heat within the boiler water.

- classroom definition: it heats the feedwater and acts as a storage while it removes oxygen and other gases

- three basic types are spray, tray (this one is less important), and column.

- there is a safety valve on this device.

Front 5

Economizer

Back 5

- A feedwater heater that heats feedwater by passing it through a finned-tube heat exchanger placed in the order of gases of combustion.

- used to reclaim heat from the hot gases of combustion.

- Increases boiler efficiency.

- located in the breeching between the outlet damper and the chimney, where gases of combustion make their last pass in the boiler.

- sufficient draft is needed to overcome these tubes, typically forced and induced draft are combined.

- the tubes must be kept clean of soot (soot retards heat transfer because it insulates the surface).

Front 6

Feedwater Heater

Back 6

- A device used to heat feedwater before it enters the boiler.

- two main reasons to use one is to improve energy efficiency by recovering waste heat and water quality.

- it preheats feedwater thereby reducing thermal shock to the boiler.

- it acts as a reservoir for available feedwater.

- they may be heated by live steam, exhaust steam, or gases of combustion.

- can be located on the suction side or discharge side of the boiler feedwater pump or in the breeching.

Front 7

Feedwater Line

Back 7

- The pipeline that carries the feedwater from the feedwater pump to the boiler

- must have a check valve and stop valve located near the shell of the boiler

Front 8

Feedwater Pump

Back 8

- A pump that takes water from the feedwater heater and delivers it to the boiler at the proper pressure

- must deliver the quantity of water necessary to maintain the NOWL in the boiler

- may be the centrifugal, turbine, or reciprocating type.

Front 9

Feedwater Regulator

Back 9

A device that maintains the water level in a boiler by controlling the amount of feedwater pumped to the boiler

Front 10

Float Feedwater Regulator

Back 10

- A feedwater Regulator that contains a steel or copper float ball connected to a switch by a linkage

- found on package firetube or watertube boilers where feedwater pumps run either intermittently or continuously

Front 11

Gauge Glass

Back 11

- A primary water level indicator that consists of a glass column, usually attached to a water column, that indicates water level

- ASME code requires that a high pressure steam boiler be installed with at least one of these.

- the brass gaskets allow room so the glass doesn’t break.

- there are two connections, a water connection and a steam connection.

- maximum pressure allowed is 400 psi.

Front 12

Low-water Fuel Cutoff

Back 12

- A control that secures the burner in the event of a low-water condition

- the primary function of this is to deenergize the burner limit circuit and shut down the burner if the water level in the boiler drops below the safe operating level

- located slightly below the NOWL

-to test this you open its personal drain (water column drain valve) and allow the water inside to drain out. An alarm should sound.

Front 13

Normal Operating Water Level (NOWL)

Back 13

The water level designated by the manufacturer as being the proper water level for safe boiler operation

Front 14

One-Element Feedwater Regulator

Back 14

- A feedwater regulator that regulates the amount of feedwater by measuring only the actual water level in the boiler

- Typically used on smaller package boilers

- basic types include: float, thermoexpansion, and thermohydraulic

Front 15

Open Feedwater Heater

Back 15

- A feedwater heater in which steam and feedwater mix with each other at atmospheric pressure to raise the temperature of water

- located above the feedwater pump and is connected to the suction side of the pump

- equipped with a safety valve, pressure gauge, and thermometer.

Front 16

Reciprocating Feedwater Pump

Back 16

- A positive-displacement pump that uses steam to apply pressure to a large piston in one cylinder connected to a small piston in another cylinder that pumps the water.

- low viscosity, steady flow.

- a positive displacement type pump which is forced by piston.

- it does not discharge the fluid continuously.

- the pressure does not affect flow rate in reciprocating pumps.

- it is used to pump low viscous fluid.

- reciprocating pump viscosity of fluid does not affect the discharge rate.

- efficiency is high.

- it does not have any problem with priming.

- it uses piston cylinder device to transfer energy to fluid.

- these are heavier compared to centrifugal pump.

- these give higher heads at low discharge.

- these are costly.

- these require higher maintenance.

Front 17

Shrink

Back 17

- The process where the water level in a boiler momentarily drops with a decrease in steam demand

- occurs when the steam demand decreases, steam is not removed as fast as it is generated resulting in a temporary increase in pressure.

- less steam leaves the boiler and water level drops, resulting in a false signal to a feedwater regulator to increase feedwater flow to the boiler.

- the boiler water level can rise above the NOWL which can cause priming and/or carryover.

Front 18

Swell

Back 18

- The process where the water level in a boiler momentarily rises with an increase in steam demand

- when the steam load suddenly increases, more steam leaves the boiler, decreasing pressure, turning more water into steam and taking up space.

- the rise in water level sends a false signal to the feedwater regulator to decrease feedwater flow to the boiler.

- the water level can fall below the NOWL

Front 19

Thermoexpansion Feedwater Regulator

Back 19

- A feedwater regulator with a thermostat that expands and contracts with exposure to steam and moves a linkage that modulates a regulator valve

- found on larger watertube boilers where feedwater pumps run continuously

Front 20

Thermohydraulic Feedwater Regulator

Back 20

- A feedwater regulator with a regulating valve, a bellows, a generator, and stop valves that varies feedwater flow in direct response to changes in the boiler water level by using changes in temperature to create changes in hydraulic pressure

- found on larger watertube boilers where feedwater pumps run continuously

Front 21

Three-Element Feedwater Regulator

Back 21

- A feedwater Regulator that regulates the amount of feedwater by measuring the steam flow from the boiler and the feedwater flow into the boiler in addition to the water level

-effective when there are sudden fluctuations in the steam load and in boilers equipped with economizers where there is a considerable drop in feedwater pressure

Front 22

Try Cock

Back 22

- Valves located on the water column of a boiler that are used to determine the boiler water level if the gauge glass is not functioning

- also known as a “secondary means of water level indication.”

- top is steam, middle is steam and water, bottom is water.

- they’re not on all boilers. When operating above 250 psi they are not used.

Front 23

Turbine Feedwater Pump

Back 23

- A rotary positive-displacement pump that uses a flat impeller with small flat perpendicular fins machined into the impeller rim to discharge feedwater into the boiler

Front 24

Two-Element Feedwater Regulator

Back 24

- A feedwater Regulator that regulates the amount of feedwater by measuring the steam flow from the boiler in addition to the water level

- normally used on larger package boilers with loads that do not fluctuate dramatically but need to be closely followed

Front 25

Variable-Speed Drive (VSD)

Back 25

- A motor controller used to vary the frequency of the electrical signal supplied to an AC motor in order to control its rotational speed. Also called a variable-frequency drive.

- can save energy because it can precisely control the motor speed.

- keeps motor from burning out.

Typical uses of this include:

1: significantly varying boiler operating pressures such as four night setbacks, plant slowdowns, or significant process-load variances.

2: operating the boiler at a pressure more than 30 psig below the safety-valve setting.

3: continuously running centrifugal pump applications where the motor horsepower is 15 HP and greater.

Front 26

Water Column

Back 26

- A boiler fitting that reduces the turbulence/oscillation of water to provide an accurate water level in the gauge glass

- minimum pipe diameter of 1” according to ASME.

- there are two connections, water and steam. Steam is the top connection and water is the bottom connection.

- also serves as a fitting so that a gauge glass, try cocks, high- and low-water alarm whistles, and gauge glass and water column blowdown lines can be attached.

- located so that the lowest visible part of the gauge glass is 2” to 3” above the top of the tubes on a firetube boiler. On watertube boilers, it is located so that the lowest visible part of the gauge glass is 2” above the lowest permissible water level as specified by the manufacturer

- state of MA does not allow valves between boiler and water column (a valve can fail)

- the “T’s” are used for inspecting

Front 27

Feedwater Regulator

Back 27

Maintain a constant water level in a boiler

Front 28

Alarms

Back 28

- May be mounted on a water column to alert the boiler operator of a high-water or low-water condition.

- can be activated by either a float or probe actuator

Front 29

Manual Reset

Back 29

A button that you can press to reset the system and start it up again after a failure.

Front 30

Condensate Pumps

Back 30

- installed at the lowest points in each building where steam is being used.

- used to pump condensate from the tank and discharge it to a surge tank or feedwater heater.

Front 31

Impeller

Back 31

- the rotating element that imparts centrifugal force to the liquid.

Front 32

Rotary Vane Pump

Back 32

- A positive-displacement pump that consists of vanes mounted to a rotor that rotates inside a cavity.

- in some cases these vanes can have variable length and/or be tensioned to maintain contact with the walls as the pump rotates.

Front 33

Screw Pump

Back 33

- A positive-displacement (PD) pump that uses one or several screws to move fluids or solids along the screw(s) axis.

- in its simplest form (the Archimedes’ screw pump), a single screw rotates in a cylindrical cavity, thereby moving the material along the screw’s spindle.

Front 34

Low-Water Fuel Cutoffs Picture

Back 34

Back (Definition)

Front 35

Auxiliary Low-Water Fuel Cutoffs Picture

Back 35

Back (Definition)

Front 36

Displacer-Type Low-Water Fuel Cutoffs Picture

Back 36

Back (Definition)

Front 37

Water Columns Picture

Back 37

Back (Definition)

Front 38

Water Column Location Picture

Back 38

Back (Definition)

Front 39

Gauge Glass Types Picture

Back 39

Back (Definition)

Front 40

Try Cocks Picture

Back 40

Back (Definition)

Front 41

Blowdown Valves Picture

Back 41

Back (Definition)

Front 42

Float Feedwater Regulator Picture

Back 42

Back (Definition)

Front 43

Float Feedwater Regulators Diagram Picture

Back 43

Back (Definition)

Front 44

Thermoexpansion Feedwater Regulators Picture

Back 44

Back (Definition)

Front 45

Thermohydraulic Feedwater Regulators Picture

Back 45

Back (Definition)

Front 46

Three-Element Feedwater Regulator Diagram Picture

Back 46

Back (Definition)

Front 47

Deaerator Picture

Back 47

Back (Definition)

Front 48

Open Feedwater Heaters Picture

Back 48

Back (Definition)

Front 49

Closed Feedwater Heaters Picture

Back 49

Back (Definition)

Front 50

Economizers Picture

Back 50

Back (Definition)

Front 51

Economizers Picture

Back 51

Back (Definition)

Front 52

Centrifugal Feedwater Pump Picture

Back 52

Back (Definition)

Front 53

If the water glass breaks

Back 53

1: make sure you have the proper PPE

2: open column and glass drains

3: isolate waterglass

4: close column drain leaving glass drain open

Front 54

Installing a new water glass

Back 54

1: make sure you have the proper PPE

2: remove and clean nuts

3: clean connections

4: place nuts back-to-back on new glass followed by new brass washers then new washers. If chevron type washers, be sure to have solid edge of washers against nuts

5: put glass in place and hand tighten nuts

6: now make sure the glass is up off the metal shoulder in the bottom connection, and if red line, that the line is facing in the desired direction

7: snug up on nuts with a wrench just enough so they don’t leak, no tighter!

8: now warm the glass up by opening the steam connection

9: when glass is warm, open the water connection

10: close waterglass drain

11: check operation of column and glass by blowing them down

Front 55

Water Column & Glass Blowdown

Back 55

- when you blowdown a water column and gauge glass you blowdown a water column first.

- before you blowdown a water column you need to let someone know what you’re doing.

- after blowing down a water column make sure to hit the manual reset button to turn the burner back on after it turns off because of the “low-water fuel cut-off.”

1: open water column drain valve wide, while blowing, water level in the glass should disappear. After blowing, close water column drain valve, after a few seconds delay, water should return to the glass rapidly. The column is blown before the glass to remove any sediment in the column and so as not to plug the lower waterglass connection.

2: open the waterglass drain valve wide, water should disappear from the waterglass, after blowing, close waterglass drain valve, water level should reappear rapidly in the waterglass

3: close the top waterglass connection. With only the bottom waterglass connection opened, open the waterglass drain valve. After blowing, close waterglass drain valve and open the top waterglass connection. Water should rapidly return to the waterglass.

4: close the bottom waterglass connection. With only the top waterglass connection opened, open the waterglass drain valve. After blowing, close waterglass drain valve and open the bottom waterglass connection. Water should rapidly return to the waterglass.

5: now test the tri-cocks. The top tri-cock should blow steam, the bottom tri-cock should blow water, and the middle connection could blow either water or steam, it will be hard to tell which.

Front 56

Water Column & Glass Notes

Back 56

- when you blowdown a water column and gauge glass you blowdown a water column first.

1: if the top waterglass connection is closed or plugged while the boiler is in operation, once the steam in the top half of the waterglass condenses, the water level in the glass would quickly rise and completely fill the glass

2: if the bottom waterglass connection is closed or plugged while the boiler is in operation, steam entering the glass through the top connection would condense slowly filling the waterglass completely

Front 57

Changing a gauge glass

Back 57

- The gauge glass is used to tell the water level in the boiler. It is usually blown down at the change of each watch. Because of this, it is subject to a lot of deterioration. The glass will either start to leak heavily or simply shatter. Either way, it must be changed.

- don’t touch the gauge glass with bare hands because it can ruin the glass by leaving oil residue on it.

- the steam valve is opened first because it lets you know if there’s a leak and to temper it

- blocked valves can give an inaccurate water level reading.

1: make sure you have the proper PPE before doing anything to the gauge glass.

2: shut the upper and lower glass connections with the chains connected to the gauge glass valve handles. Make sure they are tight.

3: open the drain under the glass to drain all the water out of the glass. Remove the protector rods around the perimeter of the glass.

4: gently loosen the top and bottom nuts and lift them off their threads

5: if the glass is broken in pieces, use a pair of pliers to remove the glass. Carefully clean out the upper and especially lower connection of all loose pieces.

6: take out a new glass and confirm that it is the correct length. On the bench, assemble the new glass with the nuts going on first, the correct sized washers next, and finally the thin brass washers.

7: take the assembly to the boiler and insert the top of the new glass first into the upper connection. The bottom of the new glass should, if properly sized, just clear the threads on the bottom connection. Drop the bottom of the glass into the bottom connection until it hits bottom.

8: push down on the nuts to seat the washers and catch the nuts on the threads. Tighten carefully.

9: before the nuts are fully tightened, make sure the red stripe on the back of the glass is pointing directly away from where it will be seen. This will ensure that when the operator looks at the glass to see the level, he will see a broad red stripe that will easily identify the water level.

10: after turning the glass to the appropriate direction, lift it up slightly to keep it from resting on the bottom connection. If the glass were allowed to rest on the bottom connection, the rapid expansion of the brass would split the glass and cause you to have to change the glass again.

11: hold the glass up and in the correct direction as you tighten the nuts with your hands only. When the nuts are tight, tighten them one flat more with a wrench.

12: crack the upper connection and allow steam to “temper” the glass and bring it up to temperature

13: after a few minutes of “tempering,” open the bottom (water) connection slowly, and close the drain. The level should “jump” up into the glass.