00:00:00.030 please subscribe to our channel for 00:00:02.60000:00:02.610 latest updates don't forget to press the 00:00:05.09000:00:05.100 bell icon industrial plants need steam 00:00:10.04000:00:10.050 for heating and other processes boilers 00:00:13.28000:00:13.290 are commonly used to provide this steam 00:00:15.49000:00:15.500 you may be called on to operate the 00:00:18.14000:00:18.150 boilers in your plant the first step 00:00:20.57000:00:20.580 towards safe and productive operation of 00:00:22.93900:00:22.949 boilers is a good working knowledge of 00:00:25.40000:00:25.410 boiler fundamentals the function of 00:00:27.85900:00:27.869 boilers is to produce steam steam is 00:00:30.95000:00:30.960 produced by heating water to its boiling 00:00:33.02000:00:33.030 point when water reaches its boiling 00:00:35.15000:00:35.160 point it changes from a liquid to a 00:00:37.54900:00:37.559 vapor it's this vapor that we call steam 00:00:40.36900:00:40.379 so basically to produce steam you need 00:00:43.40000:00:43.410 two things water and heat to generate 00:00:46.40000:00:46.410 the heat needed for steam production 00:00:48.58000:00:48.590 boilers rely on the process of 00:00:51.17000:00:51.180 combustion that is they burn fuel to 00:00:53.72000:00:53.730 provide the heat required in simple 00:00:56.47900:00:56.489 terms there are four requirements for 00:00:58.63900:00:58.649 combustion which will illustrate on a 00:01:00.83000:01:00.840 combustion triangle one requirement is 00:01:03.92000:01:03.930 fuel most boilers burn oil natural gas 00:01:07.01000:01:07.020 or coal the second requirement is air 00:01:10.34000:01:10.350 more specifically air contains the 00:01:12.80000:01:12.810 oxygen needed for combustion the third 00:01:15.85900:01:15.869 requirement is heat heat is required to 00:01:18.56000:01:18.570 raise the temperature of the fuel air 00:01:20.17900:01:20.189 mixture to a point where a chemical 00:01:22.34000:01:22.350 reaction or ignition takes place the 00:01:25.46000:01:25.470 chemical reaction is the fourth 00:01:27.05000:01:27.060 requirement if any one of the 00:01:29.84000:01:29.850 requirements is missing combustion will 00:01:32.21000:01:32.220 not occur the two requirements for steam 00:01:35.60000:01:35.610 production are water and heat the heats 00:01:38.45000:01:38.460 provided by combustion boilers are 00:01:41.21000:01:41.220 designed to allow the requirements for 00:01:43.49000:01:43.500 steam production and combustion to come 00:01:45.71000:01:45.720 together let's see how by looking at a 00:01:48.35000:01:48.360 boilers basic operating principles we'll 00:01:52.52000:01:52.530 assemble a simplified boiler this is a 00:01:55.55000:01:55.560 container or shell with water in it 00:01:58.37000:01:58.380 the water takes care of one of the 00:02:00.35000:02:00.360 requirements for steam will also add a 00:02:03.46900:02:03.479 pipe to provide a continuous supply of 00:02:05.92900:02:05.939 fuel to the combustion area that is the 00:02:09.02000:02:09.030 area beneath the shell heat from the 00:02:11.39000:02:11.400 flame satisfies the second 00:02:13.44000:02:13.450 acquirement for steam production as the 00:02:16.05000:02:16.060 shell heats up heat is transferred from 00:02:18.47900:02:18.489 the shell to the water and the water 00:02:20.97000:02:20.980 boils producing steam but a boiler 00:02:24.24000:02:24.250 modeled on this example won't work for 00:02:26.55000:02:26.560 industrial applications 00:02:28.32000:02:28.330 first of all the shell is open to the 00:02:30.60000:02:30.610 atmosphere so there's no way to collect 00:02:33.03000:02:33.040 the steam in addition as the water boils 00:02:36.24000:02:36.250 to steam there is no way to replenish it 00:02:38.87000:02:38.880 without water the shell could overheat 00:02:41.75900:02:41.769 and be damaged given these factors we'll 00:02:45.27000:02:45.280 have to make some changes first we'll 00:02:48.33000:02:48.340 cover the shell to prevent the steam 00:02:50.10000:02:50.110 from escaping then we'll add a steam 00:02:52.97900:02:52.989 outlet line to collect the steam and 00:02:55.08000:02:55.090 route it to where it can be used we also 00:02:57.80900:02:57.819 need a way to supply water to the shell 00:03:00.30000:03:00.310 so it won't boil dry so we'll add a feed 00:03:04.41000:03:04.420 water line it will provide a continuous 00:03:07.58900:03:07.599 supply of water to replace the water 00:03:09.56900:03:09.579 that's changed to steam now we have a 00:03:12.63000:03:12.640 boiler that can heat water produce steam 00:03:15.12000:03:15.130 and route it out of the shell to where 00:03:17.28000:03:17.290 it's required but this design is still 00:03:20.09900:03:20.109 not as efficient as it could be can you 00:03:22.74000:03:22.750 think of a reason why not 00:03:24.36000:03:24.370 with this design much of the heat in the 00:03:26.69900:03:26.709 combustion area escapes to the 00:03:28.62000:03:28.630 atmosphere this heat is wasted because 00:03:31.44000:03:31.450 it doesn't go toward the production of 00:03:33.42000:03:33.430 steam this boiler can be modified 00:03:36.18000:03:36.190 further to make it more efficient by 00:03:38.49000:03:38.500 adding an insulated casing we can 00:03:41.12900:03:41.139 minimize the heat loss but this creates 00:03:43.47000:03:43.480 another problem the flame goes out 00:03:46.31900:03:46.329 because the casing cuts off the source 00:03:48.56900:03:48.579 of air to correct this we'll add a fan 00:03:51.84000:03:51.850 to supply air to the boiler and an 00:03:54.84000:03:54.850 outlet to remove combustion gases 00:03:57.37900:03:57.389 although this design is still greatly 00:03:59.94000:03:59.950 simplified now we at least have a boiler 00:04:02.87900:04:02.889 that provides a constant supply of steam 00:04:05.30900:04:05.319 efficiently heat transfer is a natural 00:04:08.78900:04:08.799 process that occurs anytime there's a 00:04:11.30900:04:11.319 difference in temperature heat naturally 00:04:13.80000:04:13.810 transfers from a hotter object to a 00:04:15.87000:04:15.880 colder object basically heat transfer 00:04:18.96000:04:18.970 occurs in three ways 00:04:20.67000:04:20.680 radiation convection and conduction 00:04:23.51000:04:23.520 radiation is a process in which heat is 00:04:26.43000:04:26.440 transfer 00:04:27.21000:04:27.220 through electromagnetic waves all matter 00:04:30.36000:04:30.370 gives off some radiant energy in the 00:04:32.79000:04:32.800 form of electromagnetic waves but the 00:04:36.57000:04:36.580 best example is probably the Sun it 00:04:39.54000:04:39.550 gives off vast amounts of radiant energy 00:04:41.73000:04:41.740 as the sun's radiant energy travels 00:04:44.49000:04:44.500 through space some of the 00:04:46.17000:04:46.180 electromagnetic waves contact the earth 00:04:48.39000:04:48.400 some of these waves are reflected back 00:04:51.06000:04:51.070 into space but others are absorbed by 00:04:53.52000:04:53.530 the earth only the waves that travel in 00:04:56.85000:04:56.860 a direct line of sight between the Earth 00:04:58.86000:04:58.870 and the Sun come into contact with the 00:05:01.32000:05:01.330 earth the energy contained in the waves 00:05:03.60000:05:03.610 is absorbed by the earth as heat that 00:05:06.03000:05:06.040 warms the earth the amount of heat 00:05:08.46000:05:08.470 transferred depends on the number of 00:05:10.49000:05:10.500 electromagnetic waves absorbed a second 00:05:14.37000:05:14.380 type of heat transfer is convection 00:05:16.73000:05:16.740 convection is the transfer of heat 00:05:19.17000:05:19.180 within a fluid that is a liquid or a gas 00:05:22.29000:05:22.300 it's caused by a mixing action within 00:05:25.56000:05:25.570 the fluid to demonstrate convection we 00:05:29.40000:05:29.410 filled a beaker with water and set it on 00:05:31.44000:05:31.450 a hot plate we'll also add some dye to 00:05:34.23000:05:34.240 show the mixing action as the bottom of 00:05:37.17000:05:37.180 the beaker heats up the temperature of 00:05:39.42000:05:39.430 the water closest to the bottom 00:05:40.89000:05:40.900 increases as the temperature increases 00:05:43.53000:05:43.540 the water becomes lighter or less dense 00:05:46.77000:05:46.780 so it flows upward the warmer water 00:05:50.55000:05:50.560 mixes with the cooler water near the top 00:05:52.89000:05:52.900 of the beaker and heat transfer occurs 00:05:55.43000:05:55.440 this type of heat transfer is known as 00:05:58.23000:05:58.240 free or natural convection because the 00:06:01.32000:06:01.330 movement of the fluid occurs naturally 00:06:04.04000:06:04.050 convection heat transfer that's produced 00:06:06.57000:06:06.580 mechanically is called forced convection 00:06:09.68000:06:09.690 many buildings have forced convection 00:06:12.06000:06:12.070 heating systems these systems use fans 00:06:15.15000:06:15.160 to force warm air into rooms the warm 00:06:19.02000:06:19.030 air then mixes with the cooler air in 00:06:21.00000:06:21.010 the room and convection heat transfer 00:06:23.25000:06:23.260 occurs a third type of heat transfer is 00:06:27.06000:06:27.070 conduction conduction is the transfer of 00:06:30.30000:06:30.310 heat through a solid object or between 00:06:32.85000:06:32.860 two objects as a result of physical 00:06:35.52000:06:35.530 contact for example if we heat the 00:06:40.11000:06:40.120 middle of a steel 00:06:41.04000:06:41.050 Brod the end will heat up as well the 00:06:43.55900:06:43.569 heat transfer from one end of the raw to 00:06:46.68000:06:46.690 the other is due to conduction we've now 00:06:50.27900:06:50.289 seen the principles behind radiation 00:06:52.58900:06:52.599 convection and conduction the three main 00:06:55.46900:06:55.479 types of heat transfer are radiation 00:06:58.01000:06:58.020 convection and conduction each of these 00:07:01.37900:07:01.389 types is involved in transferring heat 00:07:03.80900:07:03.819 from the burning fuel to the water in a 00:07:06.21000:07:06.220 boiler to see how we'll use this example 00:07:10.43000:07:10.440 this type of boiler is called a water to 00:07:13.74000:07:13.750 boiler but the heat transfer principles 00:07:16.43900:07:16.449 at work apply to just about all boilers 00:07:19.17000:07:19.180 the boiler has a series of tubes and two 00:07:23.76000:07:23.770 drums which distribute water to the 00:07:25.86000:07:25.870 tubes the tubes form a wall around the 00:07:29.12900:07:29.139 combustion area this is the area where 00:07:31.98000:07:31.990 heat is generated when fuel burns in a 00:07:35.73000:07:35.740 boiler radiant energy in the form of 00:07:38.01000:07:38.020 electromagnetic waves is produced these 00:07:41.12900:07:41.139 waves travel through the combustion area 00:07:43.30900:07:43.319 the waves in a direct line of sight with 00:07:46.35000:07:46.360 the tubes make contact with the outer 00:07:48.39000:07:48.400 tube surfaces and the tubes absorb heat 00:07:51.51000:07:51.520 this is radiant heat transfer the 00:07:55.23000:07:55.240 burning fuel also produces combustion 00:07:57.60000:07:57.610 gases as these hot gases pass through 00:08:00.80900:08:00.819 the boiler they transfer heat to the 00:08:03.33000:08:03.340 tubes as well 00:08:04.58900:08:04.599 this is convection heat transfer as the 00:08:08.24900:08:08.259 outer surfaces of the tubes absorb heat 00:08:10.52900:08:10.539 conduction heat transfer occurs heat is 00:08:13.95000:08:13.960 transferred from the outer surface to 00:08:15.99000:08:16.000 the cooler inner surface then heat is 00:08:19.11000:08:19.120 transferred from the inner surface to 00:08:21.62900:08:21.639 the water flowing through the tube 00:08:25.18900:08:25.199 convection heat transfer also occurs as 00:08:28.20000:08:28.210 the warmer water mixes with cooler water 00:08:31.21900:08:31.229 when enough heat has been transferred to 00:08:33.71900:08:33.729 raise the water temperature to the 00:08:35.51900:08:35.529 boiling point steam is produced when a 00:08:38.51900:08:38.529 boiler is working properly the heat 00:08:41.13000:08:41.140 produced by the burning fuel will be 00:08:43.13900:08:43.149 readily transferred to the water in the 00:08:45.26900:08:45.279 tubes 00:08:45.81000:08:45.820 however there are problems that can 00:08:48.56900:08:48.579 interfere with heat transfer one of 00:08:51.32900:08:51.339 these problems is a condition called 00:08:53.34000:08:53.350 scale 00:08:55.34000:08:55.350 scale is the buildup of solid impurities 00:08:58.80000:08:58.810 on boiler components that contain water 00:09:01.61000:09:01.620 the boilers feed water supply may 00:09:04.50000:09:04.510 contain impurities these impurities coat 00:09:08.10000:09:08.110 the surfaces insulate them and restrict 00:09:10.89000:09:10.900 their ability to transfer heat if the 00:09:14.01000:09:14.020 surfaces can't transfer heat to the 00:09:15.96000:09:15.970 water the tube can overheat and rupture 00:09:19.29000:09:19.300 a heat transfer problem can also occur 00:09:23.10000:09:23.110 the feed water supply stops for any 00:09:25.92000:09:25.930 reason without a continuous supply of 00:09:28.56000:09:28.570 feed water the boiler may boil dry with 00:09:32.73000:09:32.740 no water to remove the heat the two 00:09:35.10000:09:35.110 metal rapidly overheats and severe 00:09:37.59000:09:37.600 damage may result in boilers that burn 00:09:40.95000:09:40.960 coal or oil another problem that can 00:09:43.86000:09:43.870 affect heat transfer is the buildup of 00:09:46.05000:09:46.060 suit suits created by ash and unburned 00:09:49.32000:09:49.330 fuel particles in the combustion gases 00:09:51.50000:09:51.510 so it buildup insulates the surfaces 00:09:54.39000:09:54.400 preventing good heat transfer when this 00:09:57.75000:09:57.760 occurs the amount of heat transfer to 00:10:00.15000:10:00.160 the water decreases as a result heat is 00:10:03.48000:10:03.490 wasted it escapes with the gases routed 00:10:06.32900:10:06.339 out of the boiler reducing boiler 00:10:08.37000:10:08.380 efficiency the last problem we'll look 00:10:11.31000:10:11.320 at is improper warmup this may occur if 00:10:14.55000:10:14.560 the boiler isn't started up correctly 00:10:17.21000:10:17.220 water tubes and other metal parts expand 00:10:20.57900:10:20.589 when they're heated if the boiler hasn't 00:10:23.10000:10:23.110 been operated for a while and then it's 00:10:25.44000:10:25.450 rapidly heated its metal parts may 00:10:27.99000:10:28.000 expand at different rates 00:10:29.57900:10:29.589 causing some parts to bend or break to 00:10:33.39000:10:33.400 protect the boiler heat must be applied 00:10:35.43000:10:35.440 gradually to ensure that all the metal 00:10:38.01000:10:38.020 components expand at the same rate 00:10:40.88000:10:40.890 basically fire tube boilers route hot 00:10:44.07000:10:44.080 combustion gases through metal tubes the 00:10:47.07000:10:47.080 tubes run through a shell filled with 00:10:49.07900:10:49.089 water fire tube boilers vary in design 00:10:52.89000:10:52.900 but most operate under similar 00:10:55.23000:10:55.240 principles the combustion area for this 00:10:58.74000:10:58.750 one is here 00:10:59.70000:10:59.710 a group of horizontal fire tubes routes 00:11:03.24000:11:03.250 combustion gases through the boiler 00:11:05.48000:11:05.490 there's also an outlet for the gas 00:11:08.46000:11:08.470 a feedwater line and a steam outlet line 00:11:12.85900:11:12.869 during operation water enters through 00:11:15.78000:11:15.790 the feed water line the water level is 00:11:18.74900:11:18.759 maintained above the fire tubes to 00:11:21.15000:11:21.160 protect the tubes from overheating 00:11:23.53900:11:23.549 fuel and air enter the combustion area 00:11:26.40000:11:26.410 the burning fuel transfers heat to the 00:11:29.22000:11:29.230 water in the shell the hot gases flow 00:11:32.78900:11:32.799 through the fire tubes and additional 00:11:35.22000:11:35.230 heat is transferred to the water 00:11:36.80900:11:36.819 surrounding them each time the gases are 00:11:40.55900:11:40.569 routed through the shell it's called a 00:11:42.60000:11:42.610 pass the gases pass through two times in 00:11:46.04900:11:46.059 this example so it's a two pass boiler 00:11:49.48900:11:49.499 the combustion gases flow out of the 00:11:52.47000:11:52.480 boiler here in this example as the water 00:11:56.03900:11:56.049 in the boiler is heated some of it turns 00:11:58.35000:11:58.360 to steam the steam water mixture is 00:12:01.07900:12:01.089 lighter than the cooler water in the 00:12:02.93900:12:02.949 boiler so it tends to rise steam 00:12:06.74900:12:06.759 collects above the water level then it 00:12:09.44900:12:09.459 flows through the outlet and into the 00:12:11.28000:12:11.290 plant the feed water which is cooler and 00:12:13.94900:12:13.959 heavier than the steam water mixture 00:12:16.07900:12:16.089 flows to the bottom of the boiler it's 00:12:18.68900:12:18.699 heated in the combustion area and the 00:12:20.81900:12:20.829 cycle continues 00:12:22.16900:12:22.179 generally speaking water-tube boilers 00:12:24.56900:12:24.579 use tubes to route water and steam 00:12:27.32900:12:27.339 through the boiler the combustion gases 00:12:29.81900:12:29.829 flow past the outside surfaces of the 00:12:32.60900:12:32.619 tubes let's examine this principle in 00:12:35.42900:12:35.439 more detail water-tube boilers may vary 00:12:39.29900:12:39.309 in design but most of them operate in 00:12:41.75900:12:41.769 basically the same way this particular 00:12:44.85000:12:44.860 boiler consists of a series of water 00:12:47.10000:12:47.110 tubes and two drums the drums distribute 00:12:51.21000:12:51.220 water to the tubes the water tubes 00:12:53.93900:12:53.949 connect the drums and form a wall around 00:12:56.22000:12:56.230 the combustion area of the boiler this 00:12:59.00900:12:59.019 is where heat is generated water is fed 00:13:02.36900:13:02.379 into the upper drum through a feed water 00:13:04.37900:13:04.389 inlet line the water tubes and the lower 00:13:07.53000:13:07.540 drum are completely filled with water 00:13:09.94900:13:09.959 the upper drum is only filled to a 00:13:12.50900:13:12.519 certain level this provides space for 00:13:14.99900:13:15.009 steam to collect so the upper drum is 00:13:17.97000:13:17.980 often called the steam drum as 00:13:21.07900:13:21.089 fuel is burned in the combustion area 00:13:22.97000:13:22.980 heat is transferred to the adjacent 00:13:25.40000:13:25.410 water tubes the combustion gases then 00:13:28.73000:13:28.740 flow out of the boiler water circulates 00:13:31.81900:13:31.829 from the upper drum through the water 00:13:33.73900:13:33.749 tubes and into the lower drum the lower 00:13:36.61900:13:36.629 drum is often referred to as the mud 00:13:39.19900:13:39.209 drum from the lower drum the water is 00:13:42.65000:13:42.660 distributed to the water tube 00:13:44.21000:13:44.220 surrounding the combustion area as the 00:13:47.48000:13:47.490 water in the tubes is heated a steam 00:13:49.61000:13:49.620 water mixture is produced the steam 00:13:53.62900:13:53.639 water mixture enters the upper drum the 00:13:56.09000:13:56.100 steam is separated from the water and 00:13:57.94900:13:57.959 routed through the steam outlet and into 00:14:00.25900:14:00.269 the plant 00:14:07.82000:14:07.830 you
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