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Boiler_Combustion_Operation_Control

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00:00:00.260
to produce steam you need heat plan
00:00:03.889 00:00:03.899 boilers rely on the process of
00:00:05.720 00:00:05.730 combustion to generate this heat to
00:00:08.570 00:00:08.580 generate heat and produce steam
00:00:10.160 00:00:10.170 efficiently boilers need the proper
00:00:12.530 00:00:12.540 combustion equipment devices like
00:00:14.780 00:00:14.790 burners and Stoker's safe and
00:00:17.570 00:00:17.580 cost-effective steam production also
00:00:19.760 00:00:19.770 requires careful control of the various
00:00:22.550 00:00:22.560 boiler flow paths for example boiler
00:00:25.849 00:00:25.859 operators need to monitor and control
00:00:27.890 00:00:27.900 air water and steam flow the main
00:00:31.790 00:00:31.800 function of all burners is the same to
00:00:34.490 00:00:34.500 inject a mixture of fuel and air into
00:00:37.160 00:00:37.170 the boilers combustion area burners are
00:00:39.830 00:00:39.840 used with fuels that mix easily with air
00:00:42.229 00:00:42.239 such as natural gas oil or a pulverized
00:00:45.650 00:00:45.660 coal this burner for example is a
00:00:48.680 00:00:48.690 typical gas burner it uses dampers or
00:00:51.979 00:00:51.989 registers to regulate the amount of air
00:00:54.229 00:00:54.239 entering the burner pipes called spuds
00:00:57.260 00:00:57.270 inject natural gas into the boiler this
00:01:00.799 00:01:00.809 is an impeller it's basically a
00:01:02.900 00:01:02.910 stationary played with openings or vanes
00:01:05.539 00:01:05.549 the cause the air to swirl around and
00:01:08.300 00:01:08.310 thoroughly mix with the gas and igniter
00:01:11.359 00:01:11.369 starts the gas air mixture burning this
00:01:14.480 00:01:14.490 one has a sparking device that uses
00:01:17.090 00:01:17.100 electrical current to create a spark
00:01:19.280 00:01:19.290 across a pair of electrodes the spark
00:01:22.490 00:01:22.500 ignites the gas air mixture as it burns
00:01:25.219 00:01:25.229 it provides heat for the boiler like all
00:01:28.670 00:01:28.680 fuel burners oil burners provide a means
00:01:31.249 00:01:31.259 to mix fuel and air for combustion but
00:01:34.310 00:01:34.320 there are some important ways in which
00:01:36.109 00:01:36.119 oil burners are unique this shows the
00:01:39.710 00:01:39.720 major parts of a typical oil burner
00:01:42.130 00:01:42.140 damper is control airflow into the
00:01:44.810 00:01:44.820 burner this is an impeller it's
00:01:48.200 00:01:48.210 basically a stationary plate with
00:01:50.270 00:01:50.280 openings or vanes that cause the air to
00:01:52.670 00:01:52.680 swirl around and thoroughly mix with the
00:01:55.100 00:01:55.110 oil since oil is a liquid it has to be
00:01:58.459 00:01:58.469 changed into a mist or atomized before
00:02:01.459 00:02:01.469 it can mix well with air and burn this
00:02:04.100 00:02:04.110 example is a mechanical atomizer
00:02:06.789 00:02:06.799 mechanical atomizers depend on the
00:02:09.260 00:02:09.270 pressure of oil passing through a nozzle
00:02:11.360 00:02:11.370 to produce a fine mist
00:02:13.570 00:02:13.580 fuel entering the atomizer blows to a
00:02:16.760 00:02:16.770 sprayer head the oil is forced through
00:02:19.670 00:02:19.680 the nozzle which breaks the oil into
00:02:22.190 00:02:22.200 droplets the droplets are sprayed into
00:02:24.980 00:02:24.990 the combustion area in the form of a
00:02:27.170 00:02:27.180 fine mist here's a type of atomizer that
00:02:30.590 00:02:30.600 can use either steam or air to atomized
00:02:33.380 00:02:33.390 oil steam or air flows through a tube
00:02:36.680 00:02:36.690 and then to a nozzle in the sprayer head
00:02:39.740 00:02:39.750 oil is supplied through the atomizer to
00:02:42.890 00:02:42.900 the sprayer head which directs the oil
00:02:45.050 00:02:45.060 into the path of the high-velocity steam
00:02:47.570 00:02:47.580 or air this breaks the oil into a fog
00:02:51.260 00:02:51.270 like mist as it enters the combustion
00:02:53.360 00:02:53.370 area this action makes the oil easier to
00:02:57.020 00:02:57.030 ignite and burn to start the oil mist
00:03:00.290 00:03:00.300 burning there is an igniter this igniter
00:03:03.530 00:03:03.540 consists of a sparking device and a
00:03:06.680 00:03:06.690 separate atomizer which serves as a
00:03:08.660 00:03:08.670 pilot for the burner a small amount of
00:03:11.750 00:03:11.760 oil is sent to the igniter atomizer the
00:03:14.540 00:03:14.550 oil flows through a nozzle which creates
00:03:17.000 00:03:17.010 the mist the spark ignites the oil mist
00:03:20.680 00:03:20.690 after a flame is established at the
00:03:23.300 00:03:23.310 igniter oil flow to the main atomizer is
00:03:26.360 00:03:26.370 started producing an oil mist then the
00:03:29.600 00:03:29.610 igniter flame ignites the oil mist and
00:03:31.880 00:03:31.890 the combustion process begins some
00:03:34.760 00:03:34.770 boilers are designed to burn solid lumps
00:03:37.280 00:03:37.290 of coal a device that supplies and burns
00:03:40.190 00:03:40.200 lumps of coal is called a stoker stokers
00:03:43.610 00:03:43.620 can also burn wood chips or other solid
00:03:45.979 00:03:45.989 fuels as well this stoker has a series
00:03:49.940 00:03:49.950 of grates to hold the coal a drive
00:03:52.610 00:03:52.620 mechanism moves the grates through the
00:03:54.770 00:03:54.780 combustion area of the boiler the coal
00:03:58.009 00:03:58.019 is stored in a hopper a gate controls
00:04:01.370 00:04:01.380 the amount of coal fed to the grates as
00:04:04.180 00:04:04.190 the coal moves along air is forced up
00:04:07.820 00:04:07.830 through the grates to provide the oxygen
00:04:10.040 00:04:10.050 needed for combustion the burning coal
00:04:13.160 00:04:13.170 moves through the boilers combustion
00:04:15.229 00:04:15.239 area and supplies the heat needed to
00:04:17.539 00:04:17.549 produce steam in the tube surrounding
00:04:19.759 00:04:19.769 the combustion area coal ash falls off
00:04:23.300 00:04:23.310 the grates into an ash bin in this topic
00:04:26.330 00:04:26.340 we saw the
00:04:27.230 00:04:27.240 major types of boiler combustion
00:04:28.909 00:04:28.919 equipment we looked at gas burners oil
00:04:31.580 00:04:31.590 burners and Stoker's let's take a minute
00:04:34.279 00:04:34.289 now to try some practice questions this
00:04:37.460 00:04:37.470 burner for example is a typical gas
00:04:39.710 00:04:39.720 burner it uses dampers or registers to
00:04:43.189 00:04:43.199 regulate the amount of air entering the
00:04:44.990 00:04:45.000 burner pipes called spuds inject natural
00:04:48.710 00:04:48.720 gas into the boiler the airflow into a
00:04:51.650 00:04:51.660 boiler provides oxygen for combustion
00:04:54.400 00:04:54.410 gases produced during combustion flow
00:04:57.170 00:04:57.180 out of the boiler and are discharged
00:04:59.480 00:04:59.490 from the stack the flow of air and other
00:05:02.420 00:05:02.430 gases through a boiler is referred to as
00:05:05.089 00:05:05.099 draft the components typically used to
00:05:08.600 00:05:08.610 provide draft are fans there are two
00:05:11.960 00:05:11.970 basic categories of draft fans forced
00:05:14.870 00:05:14.880 draft fans and induced draft fans as
00:05:18.159 00:05:18.169 their name implies forced draft fans
00:05:21.320 00:05:21.330 force air into the boiler a forced draft
00:05:24.620 00:05:24.630 fan draws air from outside the boiler
00:05:27.260 00:05:27.270 and forces it through the burner into
00:05:29.689 00:05:29.699 the combustion area induced draft fans
00:05:32.959 00:05:32.969 create draft by drawing combustion gases
00:05:36.080 00:05:36.090 from the boiler many boilers operate
00:05:39.409 00:05:39.419 with only a forced draft fan however
00:05:42.170 00:05:42.180 some boilers need both types to provide
00:05:44.779 00:05:44.789 the proper draft for example in this
00:05:47.870 00:05:47.880 boiler the forced draft fan supplies air
00:05:50.719 00:05:50.729 to the burner then the induced draft fan
00:05:53.360 00:05:53.370 draws out the hot combustion gases the
00:05:56.450 00:05:56.460 demand pristine from a boiler is called
00:05:58.939 00:05:58.949 boiler load or steam load when boiler
00:06:02.360 00:06:02.370 load increases more fuel must be burned
00:06:04.700 00:06:04.710 to produce more steam when boiler load
00:06:07.189 00:06:07.199 decreases less fuel must be burned
00:06:10.240 00:06:10.250 changes in boiler load also require
00:06:12.740 00:06:12.750 changes in the airflow to the boiler the
00:06:15.709 00:06:15.719 mixture of fuel and air supplied to a
00:06:17.719 00:06:17.729 boiler is called the fuel to air ratio
00:06:20.110 00:06:20.120 it's important to maintain the proper
00:06:22.790 00:06:22.800 fuel air ratio to avoid combustion
00:06:25.309 00:06:25.319 problems for example if the boiler is
00:06:28.490 00:06:28.500 not getting enough air some of the fuel
00:06:30.800 00:06:30.810 entering the boiler won't burn instead
00:06:33.260 00:06:33.270 it may get carried out with the
00:06:34.999 00:06:35.009 combustion gases and wasted in some
00:06:38.629 00:06:38.639 cases unburned fuel could build
00:06:41.060 00:06:41.070 up in the boiler this build-up could
00:06:43.220 00:06:43.230 cause an explosion if the fuel were
00:06:45.140 00:06:45.150 ignited in oil fired boilers unburned
00:06:48.500 00:06:48.510 fuel may create such deposits that code
00:06:51.230 00:06:51.240 boiler tube surfaces soot buildup
00:06:53.990 00:06:54.000 interferes with heat transfer and
00:06:55.850 00:06:55.860 reduces the boilers ability to produce
00:06:58.280 00:06:58.290 steam in extreme cases you may also see
00:07:02.480 00:07:02.490 black smoke coming from the stack of an
00:07:04.580 00:07:04.590 oil burning boiler that's not getting
00:07:06.770 00:07:06.780 enough air on the other hand if a boiler
00:07:09.650 00:07:09.660 gets too much air some of the fuel is
00:07:11.840 00:07:11.850 used up to heat the extra air this heat
00:07:15.200 00:07:15.210 flows out of the boiler with the
00:07:16.850 00:07:16.860 combustion gases as a result there is
00:07:19.820 00:07:19.830 less heat available to produce steam
00:07:22.780 00:07:22.790 most boiler operating procedures specify
00:07:26.240 00:07:26.250 the proper fuel to air ratio in addition
00:07:29.240 00:07:29.250 many boiler control systems
00:07:31.220 00:07:31.230 automatically adjust the fuel and air
00:07:33.320 00:07:33.330 mixture as boiler load changes in some
00:07:36.770 00:07:36.780 boilers the air supplied to the
00:07:38.750 00:07:38.760 combustion area is preheated preheating
00:07:42.050 00:07:42.060 the air raises its temperature closer to
00:07:44.570 00:07:44.580 the point where ignition occurs this in
00:07:47.300 00:07:47.310 turn helps to ensure efficient and
00:07:49.490 00:07:49.500 complete combustion one way to heat the
00:07:53.510 00:07:53.520 air flowing into a boiler is with a
00:07:55.760 00:07:55.770 rotary air heater or pre heater this one
00:07:59.870 00:07:59.880 consists of a series of heating surfaces
00:08:02.270 00:08:02.280 or elements which are connected to a
00:08:04.580 00:08:04.590 motor driven shaft the top half of this
00:08:07.970 00:08:07.980 heater is in ductwork that routes hot
00:08:10.430 00:08:10.440 combustion gases from the boiler through
00:08:12.920 00:08:12.930 the air heater and on to the stack the
00:08:16.220 00:08:16.230 bottom half is in ductwork that directs
00:08:18.530 00:08:18.540 incoming air through the heater and on
00:08:20.870 00:08:20.880 to the boiler a seal prevents hot
00:08:24.050 00:08:24.060 combustion gases from mixing with the
00:08:26.240 00:08:26.250 air flowing to the boiler the heating
00:08:29.240 00:08:29.250 surfaces rotate through the hot
00:08:31.040 00:08:31.050 combustion gases so in this section the
00:08:34.909 00:08:34.919 heating surfaces are warmed by the hot
00:08:37.190 00:08:37.200 gases then the rotating heating surfaces
00:08:40.820 00:08:40.830 transfer heat to the cooler air flowing
00:08:43.700 00:08:43.710 to the boiler the warmed air is sent to
00:08:46.430 00:08:46.440 the boilers combustion area with this
00:08:49.700 00:08:49.710 design heat that would otherwise leave
00:08:52.130 00:08:52.140 through the stack unused
00:08:54.319 00:08:54.329 heats the air entering the boiler so the
00:08:56.900 00:08:56.910 boiler operates more efficiently the
00:08:59.539 00:08:59.549 00:09:01.549 00:09:01.559 00:09:03.939 00:09:03.949 00:09:06.619 00:09:06.629 00:09:09.169 00:09:09.179 00:09:12.350 00:09:12.360 00:09:14.629 00:09:14.639 00:09:17.090 00:09:17.100 00:09:18.829 00:09:18.839 00:09:22.460 00:09:22.470 cases unburned fuel could build up in
00:09:25.160 00:09:25.170 the boiler this build-up could cause an
00:09:27.499 00:09:27.509 explosion if the fuel were ignited one
00:09:30.919 00:09:30.929 way to heat the air flowing into a
00:09:32.720 00:09:32.730 boiler is with a rotary air heater or
00:09:35.210 00:09:35.220 pre heater for a boiler to produce steam
00:09:38.960 00:09:38.970 water has to flow through the boiler
00:09:41.449 00:09:41.459 properly one way to provide water flow
00:09:44.449 00:09:44.459 in a boiler is by a process called
00:09:46.249 00:09:46.259 natural circulation this simplified
00:09:50.119 00:09:50.129 water to boiler illustrates how it works
00:09:52.840 00:09:52.850 the boiler has two drums the upper drum
00:09:56.989 00:09:56.999 is sometimes called a steam drum and the
00:10:00.289 00:10:00.299 lower drum is often called a mud drum
00:10:03.189 00:10:03.199 there's also a series of water tubes
00:10:05.809 00:10:05.819 called risers which carry a steam water
00:10:08.689 00:10:08.699 mixture to the steam drum and this one
00:10:11.749 00:10:11.759 has a down comer which carries water
00:10:14.150 00:10:14.160 from the steam drum to the mud drum
00:10:16.239 00:10:16.249 boilers normally have several downcomers
00:10:19.309 00:10:19.319 in addition there's a feed water inlet
00:10:22.519 00:10:22.529 and a steam outlet the water tubes and
00:10:26.509 00:10:26.519 the lower drum are filled with water the
00:10:29.119 00:10:29.129 steam drum is only partially filled
00:10:31.900 00:10:31.910 there's enough space in the steam drum
00:10:34.400 00:10:34.410 to allow steam to collect as combustion
00:10:38.780 00:10:38.790 occurs the water tubes that surround the
00:10:41.179 00:10:41.189 combustion area heat up as heat is
00:10:43.879 00:10:43.889 transferred to the water in these tubes
00:10:45.919 00:10:45.929 the water becomes less dense and lighter
00:10:48.439 00:10:48.449 than the cooler water elsewhere in the
00:10:50.449 00:10:50.459 boiler some of this water turns to steam
00:10:52.939 00:10:52.949 as a result the heavier cooler water
00:10:56.329 00:10:56.339 flows downward into the lower drum and
00:10:58.789 00:10:58.799 the lighter steam water mixture flows
00:11:01.129 00:11:01.139 into the steam drum then as the cooler
00:11:04.400 00:11:04.410 water is heated it too becomes lighter
00:11:06.619 00:11:06.629 it rise
00:11:07.940 00:11:07.950 to the steam drum and is replaced by
00:11:09.860 00:11:09.870 cooler denser water the steam flows to
00:11:13.430 00:11:13.440 the plant through the steam outlet and
00:11:15.440 00:11:15.450 the water level is maintained by the
00:11:17.810 00:11:17.820 water flowing through the feed water
00:11:19.490 00:11:19.500 Inlet as long as combustion takes place
00:11:22.960 00:11:22.970 natural circulation continues not all
00:11:26.660 00:11:26.670 water-tube boilers rely on natural
00:11:28.880 00:11:28.890 circulation in some cases a circulating
00:11:31.790 00:11:31.800 water pump is used to produce the flow
00:11:33.980 00:11:33.990 of water in a boiler this type of
00:11:36.290 00:11:36.300 circulation is called controlled or
00:11:38.540 00:11:38.550 forced circulation in this example the
00:11:42.290 00:11:42.300 pump draws water from the steam drum and
00:11:44.450 00:11:44.460 forces it through the lower drum and the
00:11:46.670 00:11:46.680 risers as the water in the risers is
00:11:49.430 00:11:49.440 heated a steam water mixture is produced
00:11:52.360 00:11:52.370 water from the pump forces the steam
00:11:54.950 00:11:54.960 water mixture into the steam drum if the
00:11:58.220 00:11:58.230 pump circulates the water through the
00:11:59.840 00:11:59.850 drums and the tubes the boiler will
00:12:02.300 00:12:02.310 operate as it's supposed to
00:12:04.900 00:12:04.910 hypothetically though if the pump stops
00:12:07.280 00:12:07.290 the water will no longer circulate
00:12:09.350 00:12:09.360 properly and the boiler could boil dry
00:12:11.930 00:12:11.940 and become damaged to make sure there is
00:12:15.470 00:12:15.480 proper water flow most controlled
00:12:17.990 00:12:18.000 circulation boilers use two or more
00:12:20.450 00:12:20.460 pumps so even if one pump stops the
00:12:23.900 00:12:23.910 other pump will provide enough
00:12:25.220 00:12:25.230 circulation to prevent damage to the
00:12:27.380 00:12:27.390 tubes with this type of water to boiler
00:12:29.930 00:12:29.940 water circulation depends on the
00:12:32.210 00:12:32.220 differences in density between water and
00:12:34.460 00:12:34.470 steam mechanical devices such as pumps
00:12:38.060 00:12:38.070 are not needed this method of
00:12:40.250 00:12:40.260 circulation is called natural
00:12:41.810 00:12:41.820 circulation one way in which boilers are
00:12:45.320 00:12:45.330 made more efficient is by heating the
00:12:47.480 00:12:47.490 feed water before it enters the boiler
00:12:49.460 00:12:49.470 if the feed water is preheated the
00:12:52.370 00:12:52.380 boiler will require less fuel to produce
00:12:54.500 00:12:54.510 steam a device that's used to preheat
00:12:57.530 00:12:57.540 feed water is an economizer economizers
00:13:01.880 00:13:01.890 are often used in water-tube boilers an
00:13:04.600 00:13:04.610 economizer is basically a series of
00:13:07.280 00:13:07.290 water tubes located in the flow path of
00:13:09.860 00:13:09.870 the combustion gases feed water is
00:13:13.040 00:13:13.050 routed through the tubes on its way to
00:13:14.810 00:13:14.820 the steam drum the water is heated by
00:13:17.990 00:13:18.000 the hot combustion gases flowing past
00:13:20.420 00:13:20.430 the
00:13:20.879 00:13:20.889 boobs the economizer improves boiler
00:13:23.879 00:13:23.889 efficiency by making use of heat in the
00:13:26.669 00:13:26.679 combustion gases that would otherwise be
00:13:29.280 00:13:29.290 wasted the steam produced by a boiler
00:13:32.220 00:13:32.230 generally contains some moisture some
00:13:34.710 00:13:34.720 plant processes require relatively dry
00:13:37.650 00:13:37.660 steam so the moisture could be a problem
00:13:40.280 00:13:40.290 to prevent equipment damage from
00:13:42.689 00:13:42.699 moisture some boilers are equipped with
00:13:44.699 00:13:44.709 moisture separators devices that remove
00:13:47.369 00:13:47.379 moisture from steam before it's sent to
00:13:50.220 00:13:50.230 the plant one type of moisture separator
00:13:53.819 00:13:53.829 is a centrifugal separator or cyclone
00:13:56.849 00:13:56.859 separator located in the steam drum it
00:13:59.759 00:13:59.769 works by directing the steam water
00:14:01.590 00:14:01.600 mixture into a circular chamber the
00:14:04.650 00:14:04.660 circular shape of the chamber causes the
00:14:07.019 00:14:07.029 mixture to swirl around the swirling
00:14:09.449 00:14:09.459 action creates a centrifugal force this
00:14:12.929 00:14:12.939 force flings moisture droplets against
00:14:15.479 00:14:15.489 the chamber walls then the droplets run
00:14:17.879 00:14:17.889 back into the drum
00:14:19.259 00:14:19.269 the lighter steam flows out the top of
00:14:21.989 00:14:21.999 the chamber some boilers use a dryer
00:14:25.289 00:14:25.299 along with sand typical separators this
00:14:28.590 00:14:28.600 design is often found in processes where
00:14:31.079 00:14:31.089 extremely dry steam is required this
00:14:35.069 00:14:35.079 dryer consists of a series of v-shaped
00:14:37.650 00:14:37.660 plates the steam flowing through them
00:14:39.900 00:14:39.910 has to make several changes in direction
00:14:42.530 00:14:42.540 the water droplets can't change
00:14:44.909 00:14:44.919 direction as easily as the steam so most
00:14:48.179 00:14:48.189 of the droplets separate and drip back
00:14:50.129 00:14:50.139 into the drum the steam flows through
00:14:53.039 00:14:53.049 the dryer and onto the plant one type of
00:14:56.639 00:14:56.649 moisture separator is a centrifugal
00:14:58.470 00:14:58.480 separator or cyclone separator located
00:15:02.100 00:15:02.110 in the steam drum it works by directing
00:15:04.710 00:15:04.720 the steam water mixture into a circular
00:15:06.659 00:15:06.669 chamber the circular shape of the
00:15:09.569 00:15:09.579 chamber causes the mixture to swirl
00:15:11.609 00:15:11.619 around the swirling action creates a
00:15:14.369 00:15:14.379 centrifugal force this force flings
00:15:17.579 00:15:17.589 moisture droplets against the chamber
00:15:19.799 00:15:19.809 walls then the droplets run back into
00:15:22.319 00:15:22.329 the drum
00:15:23.039 00:15:23.049 00:15:25.769 00:15:25.779 the chamber

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