00:00:00.400 --> 00:00:02.150 - [Instructor] Hi, John here. 00:00:02.150 --> 00:00:03.830 In this video we're going to be looking at 00:00:03.830 --> 00:00:06.230 a coal fired power station. 00:00:06.230 --> 00:00:08.477 I'm gonna show you all of the systems that make up 00:00:08.477 --> 00:00:12.030 the coal fired power station and how they work together 00:00:12.030 --> 00:00:14.070 in order that a coal fired power station 00:00:14.070 --> 00:00:16.670 can generate electricity. 00:00:16.670 --> 00:00:19.500 By the end of the video you'll know all of the major systems 00:00:19.500 --> 00:00:22.870 that we require in order that a coal fired power station 00:00:22.870 --> 00:00:25.010 can function correctly. 00:00:25.010 --> 00:00:27.277 We'll cover the fuel system, the water system, 00:00:27.277 --> 00:00:30.400 the steam system, the electrical system 00:00:30.400 --> 00:00:33.460 and also the exhaust gas system as well. 00:00:33.460 --> 00:00:35.750 So, by the end of the video you really will know 00:00:35.750 --> 00:00:39.757 exactly how a coal fired power station works. 00:00:39.757 --> 00:00:44.630 So, let's get started with an overview of a power station 00:00:44.630 --> 00:00:47.150 and its main systems. 00:00:47.150 --> 00:00:50.025 I say main systems because there are a lot of systems 00:00:50.025 --> 00:00:52.610 that make up a coal fired power station. 00:00:52.610 --> 00:00:56.180 They all work together to produce electricity 00:00:56.180 --> 00:00:57.970 but you have major and minor systems 00:00:57.970 --> 00:01:01.200 and we're looking at the major systems. 00:01:01.200 --> 00:01:03.360 The first thing we're going to need 00:01:03.360 --> 00:01:07.260 when we build a coal fired power station is coal. 00:01:07.260 --> 00:01:11.600 The idea is that we burn fuel to release chemical energy 00:01:11.600 --> 00:01:16.600 that we can use to heat up water and create steam. 00:01:16.670 --> 00:01:18.310 So, we can see we've got a ship 00:01:18.310 --> 00:01:20.340 on the left-hand side of this diagram. 00:01:20.340 --> 00:01:23.680 The ship is delivering coal. 00:01:23.680 --> 00:01:26.290 We will unload the coal from the ship 00:01:26.290 --> 00:01:29.550 and then we use a stacker to stack the coal up 00:01:29.550 --> 00:01:32.290 in a coal yard or perhaps a coal dome 00:01:32.290 --> 00:01:35.130 or generally just a storage area. 00:01:35.130 --> 00:01:37.700 Now, we're gonna be storing thousands and thousands of tons 00:01:37.700 --> 00:01:39.090 of coal in this area 00:01:39.090 --> 00:01:43.650 so we've got to organize the coal yard or the storage area 00:01:43.650 --> 00:01:47.023 so we're not using up more space than we actually require. 00:01:47.980 --> 00:01:50.010 Once the coal has been stacked, 00:01:50.010 --> 00:01:51.807 we're going to need to reclaim it. 00:01:51.807 --> 00:01:53.190 And that essentially means that 00:01:53.190 --> 00:01:55.900 whereas we drop the coal off before into the coal yard, 00:01:55.900 --> 00:01:57.980 we're now going to pick the coal up again 00:01:57.980 --> 00:02:01.160 and start feeding it towards the power station. 00:02:01.160 --> 00:02:03.130 The reason we have a coal yard in the first place 00:02:03.130 --> 00:02:06.510 is because sometimes we may not be able to get deliveries 00:02:06.510 --> 00:02:08.470 through to the power station. 00:02:08.470 --> 00:02:11.070 So, they will store a lot of coal, 00:02:11.070 --> 00:02:13.490 sometimes enough for three or four months 00:02:13.490 --> 00:02:16.670 and we'll gradually feed to coal then to the power station 00:02:16.670 --> 00:02:19.860 without having to worry that we're gonna run out of coal. 00:02:19.860 --> 00:02:22.950 After we've reclaimed some of the coal from the coal yard, 00:02:22.950 --> 00:02:27.410 we'll send it to a silo, often termed a day silo 00:02:27.410 --> 00:02:29.760 and we'll feed the coal from the day silo 00:02:29.760 --> 00:02:32.380 to a coal pulverizer. 00:02:32.380 --> 00:02:36.360 The idea of the pulverizer is that we can pulverize the coal 00:02:36.360 --> 00:02:39.960 in order to get very fine coal dust. 00:02:39.960 --> 00:02:43.680 Inside the pulverizer, we're also going to dry the coal out 00:02:43.680 --> 00:02:48.680 using air, cooled primary air from a force draft fan. 00:02:49.160 --> 00:02:51.560 We're gonna take this air from a pre-heater 00:02:51.560 --> 00:02:53.550 so that the area is quite hot 00:02:53.550 --> 00:02:55.860 and then we'll force it into the pulverizer 00:02:55.860 --> 00:02:59.620 and as the coal is ground up into small molecules, 00:02:59.620 --> 00:03:01.820 we'll also dry it out using this air. 00:03:01.820 --> 00:03:03.900 We use the same air for combustion 00:03:03.900 --> 00:03:06.300 because it's gonna get blown into the boiler 00:03:06.300 --> 00:03:09.100 along with the coal. 00:03:09.100 --> 00:03:12.370 So, we've got our coal dust leaving the pulverizer, 00:03:12.370 --> 00:03:15.821 it's been blown pneumatically from the pulverizer 00:03:15.821 --> 00:03:18.090 to the boiler. 00:03:18.090 --> 00:03:21.550 When we get to the boiler, we're going to ignite that coal 00:03:21.550 --> 00:03:24.320 and we're going to get combustion. 00:03:24.320 --> 00:03:26.720 So, that is our fuel system. 00:03:26.720 --> 00:03:30.870 We may also use oil to fire the boiler, at least initially 00:03:30.870 --> 00:03:35.400 or natural gas which is predominantly methane gas. 00:03:35.400 --> 00:03:38.650 It all depends on the design of the boiler itself. 00:03:38.650 --> 00:03:43.320 The type of boiler we're using is a water tube boiler. 00:03:43.320 --> 00:03:46.850 Whenever you need a lot of steam at very high pressures, 00:03:46.850 --> 00:03:49.940 you're going to be using a water tube boiler. 00:03:49.940 --> 00:03:52.870 Steam turbines require steam at very high pressures 00:03:52.870 --> 00:03:55.620 and that's why we use water tube boilers 00:03:55.620 --> 00:03:59.430 but water tube boilers also generate a lot of steam. 00:03:59.430 --> 00:04:00.350 They're very large. 00:04:00.350 --> 00:04:04.030 They can be greater than 40, 50, 60 meters in height 00:04:04.030 --> 00:04:06.710 and these are the boilers that power stations 00:04:06.710 --> 00:04:10.400 in the power generation industry always use. 00:04:10.400 --> 00:04:12.730 So, let's have a look at our water circuit now 00:04:12.730 --> 00:04:15.380 because it's water that gets fed to the boiler 00:04:15.380 --> 00:04:17.930 in order to generate steam. 00:04:17.930 --> 00:04:20.570 We've got a makeup water inlet. 00:04:20.570 --> 00:04:22.743 Makeup water feeds to a deaerator. 00:04:24.300 --> 00:04:25.230 When we talk about makeup water, 00:04:25.230 --> 00:04:27.600 were essentially talking about the water that's added 00:04:27.600 --> 00:04:30.500 to the system and then treated 00:04:30.500 --> 00:04:33.400 before it becomes boiler feedwater. 00:04:33.400 --> 00:04:36.580 You can't just take water from a city grid or from a lake 00:04:36.580 --> 00:04:39.820 or a river and put it into a water tube boiler, 00:04:39.820 --> 00:04:40.920 that's not gonna work. 00:04:40.920 --> 00:04:44.590 You're gonna have a lot of corrosion and a lot of problems. 00:04:44.590 --> 00:04:47.410 So, this makeup water has to be treated, 00:04:47.410 --> 00:04:50.320 chemically and mechanically and we do that quite often 00:04:50.320 --> 00:04:51.203 in a deaerator. 00:04:52.707 --> 00:04:56.150 The deaerator is going to reduce the oxygen content 00:04:56.150 --> 00:04:59.090 and the CO2 content of the water 00:04:59.090 --> 00:05:01.050 and before the water gets to the deaerator, 00:05:01.050 --> 00:05:02.730 it's going to be filtered et cetera 00:05:02.730 --> 00:05:05.550 to take out those particles that might be floating around 00:05:05.550 --> 00:05:06.920 in the water. 00:05:06.920 --> 00:05:10.130 Then we'll go to a boiler feedwater pump. 00:05:10.130 --> 00:05:13.660 This is usually a multi-stage centrifugal pump 00:05:13.660 --> 00:05:17.790 and we will increase the pressure of our boiler feedwater 00:05:17.790 --> 00:05:21.530 and send it to our water tube boiler. 00:05:21.530 --> 00:05:24.870 The pressures involved here are actually quite high. 00:05:24.870 --> 00:05:28.220 You're looking at in excess of 200 bar 00:05:28.220 --> 00:05:32.230 which is in excess of around 3000 psi. 00:05:32.230 --> 00:05:34.980 The water will be pumped to an economizer 00:05:34.980 --> 00:05:38.140 where we'll preheat the water a little bit 00:05:38.140 --> 00:05:42.490 before we send it to the main body of the water tube boiler. 00:05:42.490 --> 00:05:46.270 So, the economizer is a nice way of preheating the water 00:05:46.270 --> 00:05:48.360 before we send it into the main part of the boiler 00:05:48.360 --> 00:05:51.740 to really start heating it up a lot more. 00:05:51.740 --> 00:05:54.240 We don't wanna feed cold water into the main part 00:05:54.240 --> 00:05:56.850 of the boiler or the furnace as we call it 00:05:56.850 --> 00:05:58.470 because if we do that 00:05:58.470 --> 00:05:59.867 then we're gonna thermal shock the boiler 00:05:59.867 --> 00:06:03.390 and that could mean that we have cracked pipes et cetera. 00:06:03.390 --> 00:06:06.410 So, we'll preheat it by sending it to the economizer. 00:06:06.410 --> 00:06:08.980 We'll then send the water around to the furnace 00:06:08.980 --> 00:06:13.140 and we'll put the water into the water tube boiler walls. 00:06:13.140 --> 00:06:17.390 They're called walls because the piping around the furnace 00:06:17.390 --> 00:06:19.650 makes up a square space 00:06:19.650 --> 00:06:22.510 similar to having four separate walls. 00:06:22.510 --> 00:06:24.950 This means we can get a lot of heat transfer, 00:06:24.950 --> 00:06:28.440 mostly via radiation to the furnace walls 00:06:28.440 --> 00:06:31.960 and then this heat is going to be absorbed via conduction 00:06:31.960 --> 00:06:36.373 into the water and our water is going to change to steam. 00:06:37.350 --> 00:06:39.080 We have different types of steam. 00:06:39.080 --> 00:06:41.010 We have wet steam and we have dry steam, 00:06:41.010 --> 00:06:43.310 superheated steam et cetera. 00:06:43.310 --> 00:06:45.160 But when we talk about wet and dry steam, 00:06:45.160 --> 00:06:49.140 we're referring to if steam has water molecules 00:06:49.140 --> 00:06:50.790 in it or not. 00:06:50.790 --> 00:06:53.040 If the steam is totally dry 00:06:53.040 --> 00:06:56.040 then it will have no water molecules in it. 00:06:56.040 --> 00:06:59.704 Steam is a colorless and odorless gas 00:06:59.704 --> 00:07:04.704 and by the time this steam vapor has reached our steam drum 00:07:06.150 --> 00:07:08.220 which is at the top of the boiler, 00:07:08.220 --> 00:07:09.830 we're gonna have wet steam. 00:07:09.830 --> 00:07:11.550 It's not gonna be completely dry yet, 00:07:11.550 --> 00:07:15.320 there's gonna be particles of moisture in the steam. 00:07:15.320 --> 00:07:19.000 That is what we see normally when we think about steam. 00:07:19.000 --> 00:07:21.710 In the steam drum will begin to separate 00:07:21.710 --> 00:07:23.340 that moisture from the steam, 00:07:23.340 --> 00:07:26.848 sometimes using steam separators or steam cyclones, 00:07:26.848 --> 00:07:29.510 sometimes using arrangement of baffles 00:07:29.510 --> 00:07:31.810 or a combination of both. 00:07:31.810 --> 00:07:35.380 We'll then send our steam to a super heater 00:07:35.380 --> 00:07:38.104 where we will really heat that steam up 00:07:38.104 --> 00:07:40.070 and although we get a slight pressure drop, 00:07:40.070 --> 00:07:42.000 we're gonna add more and more heat 00:07:42.000 --> 00:07:45.350 and the temperature of the steam is going to increase. 00:07:45.350 --> 00:07:49.320 We will then feed that steam from our super heaters 00:07:49.320 --> 00:07:53.080 into a high pressure turbine. 00:07:53.080 --> 00:07:54.900 As the steam passes through the turbine, 00:07:54.900 --> 00:07:58.430 it causes the turbine runner to rotate. 00:07:58.430 --> 00:08:01.270 So, we've taken the chemical energy of the fuel, 00:08:01.270 --> 00:08:04.230 turned it into heat, we've heated up the water, 00:08:04.230 --> 00:08:06.070 we've created high-pressure steam, 00:08:06.070 --> 00:08:08.320 we've fed it to a turbine 00:08:08.320 --> 00:08:12.900 and now we are converting that heat energy or heat 00:08:12.900 --> 00:08:17.540 into mechanical movement or kinetic energy. 00:08:17.540 --> 00:08:19.130 We're then gonna take the steam 00:08:19.130 --> 00:08:21.200 out of the high-pressure turbine. 00:08:21.200 --> 00:08:23.450 It's given up a bit of its heat already 00:08:23.450 --> 00:08:27.140 but we send it back into the boiler to be reheated 00:08:27.140 --> 00:08:31.080 so that we can send it then to an intermediate turbine. 00:08:31.080 --> 00:08:32.470 The reason we've reheated the steam 00:08:32.470 --> 00:08:35.960 is simply because we get a slight increase in efficiency 00:08:35.960 --> 00:08:37.800 so it's definitely worth doing 00:08:37.800 --> 00:08:41.000 but we feed that steam from the reheater 00:08:41.000 --> 00:08:42.550 in the water tube boiler 00:08:42.550 --> 00:08:46.030 to an intermediate pressure turbine. 00:08:46.030 --> 00:08:48.480 The process is the same as for the HP turbine 00:08:48.480 --> 00:08:50.040 or the high pressure turbine. 00:08:50.040 --> 00:08:53.240 We allow the steam to flow through the turbine, 00:08:53.240 --> 00:08:56.890 the turbine rotor rotates and then the steam exits 00:08:56.890 --> 00:08:59.070 the intermediate pressure turbine 00:08:59.070 --> 00:09:03.690 and is fed to two low pressure turbines. 00:09:03.690 --> 00:09:06.500 In the low pressure turbines, we pass the steam 00:09:06.500 --> 00:09:10.810 through the low pressure turbines, the rotors rotate 00:09:10.810 --> 00:09:14.140 and then the steam has effectively fulfilled its purpose, 00:09:14.140 --> 00:09:16.920 it's given up a lot of heat 00:09:16.920 --> 00:09:20.230 and the best thing for us to do now is to cool the steam, 00:09:20.230 --> 00:09:24.180 condense it, pump it back through a heater 00:09:24.180 --> 00:09:28.340 to the deaerator and then back to the boiler again. 00:09:28.340 --> 00:09:31.600 So, those are our water and steam circuits. 00:09:31.600 --> 00:09:33.180 So, we've covered the fuel system, 00:09:33.180 --> 00:09:34.280 we've covered the water system, 00:09:34.280 --> 00:09:36.280 we've covered the steam system. 00:09:36.280 --> 00:09:39.370 You might be wondering how do we cool down so much steam 00:09:39.370 --> 00:09:42.290 and turn it back into condensate. 00:09:42.290 --> 00:09:44.770 Well, quite often we will use a cooling tower. 00:09:44.770 --> 00:09:48.445 In our example here we have a natural draft cooling tower 00:09:48.445 --> 00:09:51.430 and essentially the cooling tower has a large reservoir 00:09:51.430 --> 00:09:52.330 in the base. 00:09:52.330 --> 00:09:56.193 We suck the water out of the bottom of the reservoir, 00:09:56.193 --> 00:09:59.295 we send it to a condenser which is a little bit 00:09:59.295 --> 00:10:02.156 like a shell and tube heat exchanger 00:10:02.156 --> 00:10:04.310 and then once we've cooled down that steam, 00:10:04.310 --> 00:10:06.960 we're going to need to reject the heat 00:10:06.960 --> 00:10:09.680 in order that we can use our cooling water again. 00:10:09.680 --> 00:10:12.920 So, we send the heated up or the hot coolant water, 00:10:12.920 --> 00:10:14.930 you could say, to the cooling tower. 00:10:14.930 --> 00:10:18.060 We'll reject that heat to atmosphere 00:10:18.060 --> 00:10:19.590 and then the process continues. 00:10:19.590 --> 00:10:22.220 The hot cooling water which has been cooled 00:10:22.220 --> 00:10:24.940 drops down into the reservoir of the tower 00:10:24.940 --> 00:10:27.643 and is pumped back to the condenser. 00:10:28.480 --> 00:10:31.500 If you wanna learn more about natural draft cooling towers 00:10:31.500 --> 00:10:34.770 and shell and tube heat exchangers, coal pulverizers, 00:10:34.770 --> 00:10:37.300 transformers et cetera then I will put links 00:10:37.300 --> 00:10:41.840 to all of those tutorials in the video description area. 00:10:41.840 --> 00:10:45.310 So now, let's have a look at a few other systems. 00:10:45.310 --> 00:10:48.380 We've got a secondary air system which passes air 00:10:48.380 --> 00:10:52.040 through a preheater and feeds it to the boiler. 00:10:52.040 --> 00:10:55.250 The primary air system which feeds to the coal pulverizer 00:10:55.250 --> 00:10:59.000 and then to the water tube boiler is also preheated. 00:10:59.000 --> 00:11:00.840 The difference between the two systems 00:11:00.840 --> 00:11:03.610 is that the primary air system is added 00:11:03.610 --> 00:11:06.180 prior to combustion occurring. 00:11:06.180 --> 00:11:08.970 It controls the rate of combustion. 00:11:08.970 --> 00:11:12.370 If we add more fuel than we need to add more air. 00:11:12.370 --> 00:11:14.300 The secondary air system controls 00:11:14.300 --> 00:11:17.050 how efficiently combustion occurs. 00:11:17.050 --> 00:11:20.400 We can actually sample the exhaust gas system 00:11:20.400 --> 00:11:22.590 and we can look at things like the oxygen levels 00:11:22.590 --> 00:11:26.070 or the CO2 levels or the carbon monoxide levels 00:11:26.070 --> 00:11:29.600 and we can determine then if we need to add more air 00:11:29.600 --> 00:11:31.940 to the boiler in order to increase 00:11:31.940 --> 00:11:34.910 our combustion efficiency or not. 00:11:34.910 --> 00:11:37.340 Large amounts of oxygen indicate that we've added 00:11:37.340 --> 00:11:39.690 too much air and perhaps not enough fuel. 00:11:39.690 --> 00:11:42.736 Large amounts of carbon monoxide 00:11:42.736 --> 00:11:46.640 not enough air and that combustion efficiency is low 00:11:46.640 --> 00:11:49.410 because combustion was not complete. 00:11:49.410 --> 00:11:50.890 So, we've covered the air systems, 00:11:50.890 --> 00:11:54.340 let's have a quick look now at the exhaust gas system. 00:11:54.340 --> 00:11:57.620 The exhaust gas system is also known as the flue gas system 00:11:57.620 --> 00:12:01.590 or the gases of combustion system. 00:12:01.590 --> 00:12:03.470 Normally, I call it the exhaust gas system 00:12:03.470 --> 00:12:06.810 although people use these terms interchangeably. 00:12:06.810 --> 00:12:09.930 The exhaust gases will pass through the preheater 00:12:09.930 --> 00:12:14.210 and some of the remaining heat from the exhaust gases 00:12:14.210 --> 00:12:18.360 is used to heat up the air which is being fed to the boiler. 00:12:18.360 --> 00:12:20.049 After that the exhaust gases will pass 00:12:20.049 --> 00:12:23.600 to an electrostatic precipitator 00:12:23.600 --> 00:12:27.550 and will effectively ionize the exhaust gas stream 00:12:27.550 --> 00:12:32.430 in order that particles are attracted to large metal plates. 00:12:32.430 --> 00:12:35.883 These metal plates have a large contact surface area. 00:12:35.883 --> 00:12:39.467 Particles in the exhaust gas stream such as fly ash 00:12:39.467 --> 00:12:43.130 will be attracted to these large surfaces 00:12:43.130 --> 00:12:44.580 and in this way we can remove them 00:12:44.580 --> 00:12:46.860 from the exhaust gas stream. 00:12:46.860 --> 00:12:49.510 Periodically, these large plates will become 00:12:49.510 --> 00:12:53.310 totally covered in these exhaust gas particles 00:12:53.310 --> 00:12:56.200 and will shape the plates or simply bang them 00:12:56.200 --> 00:12:58.710 in order that the particles fall off the plates 00:12:58.710 --> 00:13:02.540 and then go to a silo where they can be discharged 00:13:02.540 --> 00:13:05.890 to a truck or maybe they'll go to an ash pond 00:13:05.890 --> 00:13:08.190 or some sort of landfill sites. 00:13:08.190 --> 00:13:10.010 The particles that you filter out 00:13:10.010 --> 00:13:14.270 via the electrostatic precipitator can actually be sold 00:13:14.270 --> 00:13:15.720 and they'll often use these particles 00:13:15.720 --> 00:13:17.860 in the cement industry, for example. 00:13:17.860 --> 00:13:21.390 So, they will ship the particles off to a cement plant 00:13:21.390 --> 00:13:25.620 and you'll mix this ash in with the cement 00:13:25.620 --> 00:13:28.180 as part of the cement plan process. 00:13:28.180 --> 00:13:30.450 This is quite useful because if you're a power station 00:13:30.450 --> 00:13:34.080 then you don't have to pay to get rid of your ash. 00:13:34.080 --> 00:13:38.156 After the electrostatic precipitator or ESP, 00:13:38.156 --> 00:13:42.570 the exhaust gases pass through an induced draft fan 00:13:42.570 --> 00:13:47.340 and then they will flow to a desulphurization gas scrubber. 00:13:47.340 --> 00:13:50.170 The idea with the scrubber is that we are removing 00:13:50.170 --> 00:13:53.100 as much of the sulfur dioxide from the gas stream 00:13:53.100 --> 00:13:55.880 as possible before we discharge 00:13:55.880 --> 00:13:58.550 the exhaust gas to atmosphere. 00:13:58.550 --> 00:14:01.080 In order to remove the sulfur from the gas stream, 00:14:01.080 --> 00:14:05.340 we will usually use lime, limestone or ammonia 00:14:05.340 --> 00:14:08.470 and we'll spray that into a large column, 00:14:08.470 --> 00:14:10.400 it will absorb some of the sulfur, 00:14:10.400 --> 00:14:13.180 we may get ammonia sulfate for example 00:14:13.180 --> 00:14:15.780 and will form something called gypsum 00:14:15.780 --> 00:14:17.690 which can then also be sold. 00:14:17.690 --> 00:14:20.170 So, the byproduct of the process is gypsum 00:14:20.170 --> 00:14:22.500 which can be sold by the power station, 00:14:22.500 --> 00:14:25.370 again sometimes to a cement factory. 00:14:25.370 --> 00:14:28.510 I believe sometimes it's used for plastering walls 00:14:28.510 --> 00:14:31.640 and also in the agricultural industry as well. 00:14:31.640 --> 00:14:35.550 So, by selling the fly ash particles 00:14:35.550 --> 00:14:38.910 and by selling the gypsum it means that we don't have to pay 00:14:38.910 --> 00:14:41.940 to get rid of these materials. 00:14:41.940 --> 00:14:43.860 And you have to remember we're producing 00:14:43.860 --> 00:14:47.400 hundreds or thousands of tons of these byproducts 00:14:47.400 --> 00:14:49.940 of combustion every year. 00:14:49.940 --> 00:14:52.550 So, it's quite a lot of money if you have to pay 00:14:52.550 --> 00:14:55.800 to get rid of these products of combustion. 00:14:55.800 --> 00:14:57.920 Sometimes you'll actually see a cement plant 00:14:57.920 --> 00:15:02.480 located right next door to 00:15:02.480 --> 00:15:03.710 That's not a coincidence. 00:15:03.710 --> 00:15:07.330 It's because they can then convey the ash and the gypsum 00:15:07.330 --> 00:15:09.810 directly to the cement plant 00:15:09.810 --> 00:15:11.300 and in this way the cement plant 00:15:11.300 --> 00:15:13.570 has a constant stream of raw materials 00:15:13.570 --> 00:15:15.610 from the coal fired power station 00:15:15.610 --> 00:15:17.500 but they don't have to pay any shipping costs 00:15:17.500 --> 00:15:18.710 to get these materials. 00:15:18.710 --> 00:15:21.380 So, it's quite a convenient arrangement. 00:15:21.380 --> 00:15:25.090 After flue gas desulphurization FGD, 00:15:25.090 --> 00:15:27.590 the exhaust gas is then gonna flow to a stack 00:15:27.590 --> 00:15:31.120 which is a large cylindrical steel column, 00:15:31.120 --> 00:15:33.650 much like a chimney and the exhaust gases 00:15:33.650 --> 00:15:37.100 will be discharged to atmosphere. 00:15:37.100 --> 00:15:39.640 We call it a stack because of the stack effect 00:15:39.640 --> 00:15:41.310 which essentially means that hot air 00:15:41.310 --> 00:15:44.890 will rise above cooler air due to the density difference 00:15:44.890 --> 00:15:46.300 between the two. 00:15:46.300 --> 00:15:48.130 Hot air is actually less dense 00:15:48.130 --> 00:15:52.350 and that's why it rises above cold air, for example. 00:15:52.350 --> 00:15:54.230 Let's go and have a look now what happens 00:15:54.230 --> 00:15:56.820 after our turbine is in motion. 00:15:56.820 --> 00:16:00.680 Why do we even want the turbine rotors rotating? 00:16:00.680 --> 00:16:03.300 Well, we want them rotating because we're gonna connect them 00:16:03.300 --> 00:16:06.230 to a generator rotor. 00:16:06.230 --> 00:16:09.543 The rotor is gonna rotate within a generator stator 00:16:10.525 --> 00:16:12.853 and we're gonna generate alternating current. 00:16:13.780 --> 00:16:16.360 I say generate, we have to think about 00:16:16.360 --> 00:16:18.280 the first law of thermodynamics here 00:16:18.280 --> 00:16:23.280 which means we cannot generate, produce or destroy energy. 00:16:24.020 --> 00:16:26.290 All we're doing throughout the entire process 00:16:26.290 --> 00:16:30.220 is transferring energy from one form to another 00:16:30.220 --> 00:16:32.240 in order that we can get it into a form 00:16:32.240 --> 00:16:34.850 that we find very useful. 00:16:34.850 --> 00:16:36.600 The form that we find very useful 00:16:36.600 --> 00:16:40.210 is electricity, electrical energy. 00:16:40.210 --> 00:16:42.680 If we take our electricity from the generator, 00:16:42.680 --> 00:16:44.250 we pass it to a transformer, 00:16:44.250 --> 00:16:47.600 we increase the voltage significantly 00:16:47.600 --> 00:16:51.020 maybe from 20 kV up to 400 kV 00:16:51.020 --> 00:16:54.360 and then we send it to an open-air switch yard 00:16:54.360 --> 00:16:59.170 and then distribute it to a national or international grid. 00:16:59.170 --> 00:17:00.810 But throughout the entire process, 00:17:00.810 --> 00:17:05.460 all we're doing is changing the form of energy. 00:17:05.460 --> 00:17:07.210 We call it the power generation industry 00:17:07.210 --> 00:17:08.930 but we're not actually generating anything 00:17:08.930 --> 00:17:11.720 maybe we should call it the power transfer industry. 00:17:11.720 --> 00:17:14.780 We're taking the chemical energy from the fuel, 00:17:14.780 --> 00:17:17.320 we're turning it into heat, 00:17:17.320 --> 00:17:20.410 we're transferring that heat via radiation, 00:17:20.410 --> 00:17:23.980 conduction or convection to the water 00:17:23.980 --> 00:17:26.200 which then gives us steam and that steam 00:17:26.200 --> 00:17:27.900 can be sent to a turbine, 00:17:27.900 --> 00:17:31.390 we'll transfer the heat to the turbine rotors 00:17:31.390 --> 00:17:35.600 in order to give them mechanical movement or kinetic energy 00:17:35.600 --> 00:17:39.450 then we'll feed that kinetic energy to a generator 00:17:39.450 --> 00:17:42.290 and as the generator rotor rotates 00:17:42.290 --> 00:17:45.710 through the magnetic field that surrounds it, 00:17:45.710 --> 00:17:48.460 we're going to induce current flow in the windings 00:17:48.460 --> 00:17:49.960 and this essentially gives us 00:17:49.960 --> 00:17:53.940 suppose what we refer to as electricity in alternating form. 00:17:53.940 --> 00:17:56.865 And these alternating current gets passed into transformer. 00:17:56.865 --> 00:18:00.310 After transformer, we go to an open-air switch yard 00:18:00.310 --> 00:18:05.310 that is simply a large area that's full of surge arresters, 00:18:05.330 --> 00:18:08.960 lightning arresters, circuit breakers et cetera 00:18:08.960 --> 00:18:11.570 and all of those components within the open-air switch yard 00:18:11.570 --> 00:18:15.200 are there to protect the transformer 00:18:15.200 --> 00:18:18.220 and the electrical systems in the power station 00:18:18.220 --> 00:18:19.793 as well as the grid itself. 00:18:20.920 --> 00:18:22.390 So, that is essentially 00:18:22.390 --> 00:18:26.580 how a coal fired power station works. 00:18:26.580 --> 00:18:28.820 There are many different power station designs, 00:18:28.820 --> 00:18:30.820 many different power station types, 00:18:30.820 --> 00:18:34.770 some of them are very large, some of them are much smaller. 00:18:34.770 --> 00:18:37.140 They become more and more complex 00:18:37.140 --> 00:18:41.960 as you increase the megawatt capacity size 00:18:41.960 --> 00:18:44.610 and generally, the newer power stations 00:18:44.610 --> 00:18:48.003 are a lot more complex than the older style power stations. 00:18:49.230 --> 00:18:51.840 I've run out of time in this video but in our next video 00:18:51.840 --> 00:18:55.570 I'm gonna show you a coal fired power station in 3D 00:18:55.570 --> 00:18:58.270 and then I'm gonna load up separate 3D models 00:18:58.270 --> 00:19:00.780 of all of the major components associated 00:19:00.780 --> 00:19:02.710 with a coal fired power station 00:19:02.710 --> 00:19:05.560 and I'm going to show you each of these 3D models 00:19:05.560 --> 00:19:09.840 so you can understand exactly how the power station works 00:19:09.840 --> 00:19:13.658 and how each individual component works as well. 00:19:13.658 --> 00:19:17.560 steam or boilers, valves, 00:19:17.560 --> 00:19:21.650 pumps or anything else related to industrial engineering 00:19:21.650 --> 00:19:23.770 then check out our website. 00:19:23.770 --> 00:19:26.530 You can find a link in the video description area. 00:19:26.530 --> 00:19:30.670 We've got over 30 hours of engineering video tutorials 00:19:30.670 --> 00:19:31.753 much like this one. 00:19:32.654 --> 00:19:36.260 Our technical encyclopedia has over 100,000 words 00:19:36.260 --> 00:19:38.040 and hundreds of articles. 00:19:38.040 --> 00:19:41.610 We've also got quizzes and apps which will support you 00:19:41.610 --> 00:19:45.340 as you learn more and more about engineering 00:19:45.340 --> 00:19:47.130 and don't forget you can always subscribe 00:19:47.130 --> 00:19:48.750 to our YouTube channel. 00:19:48.750 --> 00:19:50.250 Thanks very much of your time.
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