 What we're going to do now is we're going to take a look at each of the different components that are within the Rankin cycle and then this consists of the pump, the boiler, the turbine, and the condenser. And we'll begin with the pump. I'm not going to go into detail with the pump because I will refer you to your fluid mechanics textbook to read about pumps. Now there are different types of pumps, centrifugal pumps, positive displacement pumps, but you can read about those in your fluids book. What I will do, however, we're going to take a look at the next component within our cycle and that's the boiler. Now the design of the boiler will depend upon what is being combusted. Now this is assuming that we're using fossil fuels. We could be using solar energy or we could also be using nuclear energy in the case of a nuclear power plant or a solar thermal power plant. But what we're going to do is we're going to look more specifically at a fossil fuel-based boiler and that's why I say combusted. And so we can have a variety of different fuels. You can be using coal, which is a solid fuel, oil, a liquid, or natural gas. Now usually natural gas, you'd have a slightly different design. And that's the combined cycle that we will look at in a later lecture. Now if you're burning a solid fuel such as coal, you need to pulverize it first. Basically grind it into a fine powder and it would be moved into the boiler using a pneumatic conveying system or air basically carrying it in and then that's where you'd have your combustion. But essentially any boiler is going to have a number of different components. We will have an economizer and we use that to heat or preheat the water. We have furnace wall tubes and that's where we're going from a water to a vapor. We have a primary super heater and that's where the fluid is going from the after it goes through the phase change from water into a vapor, then we super heat it and take it to the superheated condition before it would then go into the turbine. So those are some of the components that we would have in a standard boiler. I'm now going to draw a schematic so that we can take a look at what the boiler looks like. So there we can see the basic components of the boiler. What we have is an air preheater. So air comes in. These fins up here denote the fact that we would have heat exchange and the preheated air would come through a blower. The blower may be before you preheat but I'm just showing it here that it's coming in at the point right before the burners and then we have combustion, different forms of combustion depending upon the burner design. The flames could be going together, going up the stack in different types of combinations. But the primary heat transfer here in the beginning early stages is through radiative heat transfer which is then being transferred to the water as we have water coming in from the pump going through a preheater coming into the boiler to reduce any kind of thermal shock and then we are then going through a phase change in this region here. So the water is going from the liquid to the vapor phase. It then leaves as steam and it might be saturated steam or something around there. There may still be some water droplets in it. After that it then goes into a super heater. So it goes through the exhaust gas again and through that process we add more heat to the steam. We go into the super heated stage or state and from there we come out and we then move into the turbine. So that's basically a summary of what's going on in a boiler. Let's take a look now at a short little video clip of a sugar mill. Actually this was taken on the island of Maui in Hawaii and it's a sugar mill. So it's used for for generated process heat but it's also used for generating electricity and we'll see a little bit of a video clip of the boiler as well as the stack and the coal going into the boiler. So let's take a look at that. Now in that video clip you're able to see the entire cycle going from coal in a pile up a conveyor into a pulverizer. It's a little difficult to see the boiler which it always is in any kind of operating steam power plant because it's always enclosed. However you could see the boiler from the very large tubes or ducts that were coming out of it and then moving on into the vertical stack where there is more dropout of any kind of slag or or the byproducts of combustion that are the solid components after coal combustion and you could also see the slag being removed and then taking off site to another location and that would be used for things like cinder blocks, cinder bricks, other applications. So I'm just going to make a couple of comments here about the operation of boilers that we need to be a little careful with because you can have byproducts of combustion that can cause damage to your boilers. So depending on what you're burning is the fuel in your boiler and sometimes there can be trace elements of sulfur especially if you're burning coal and that sulfur through the combustion process can generate different oxide compounds and if they form with water water vapor being in as a byproduct of combustion that can then condense out in your stack and you ideally want to avoid that by staying above the dew point of water and rule of thumb is 15 to 20 degrees Celsius above the dew point of water in your stack also giving you a buoyant plume then so that it leaves that the downside is that it goes into the environment and so we do try to find ways of being able to remove that either by burning coals that don't have that or other types of fuel that are a little cleaner and there's a lot of cleanup that goes on in the vertical stack as well but the reason why we don't want it in our boiler and condensing out is because it'll form sulfuric acid which will lead to corrosion and will degrade the boiler over time. There's another place where we can have trouble and that is if we have oxygen in our boiler feed water so I'll just write a comment about that now. So with this one what you want to do is you want to get the oxygen out of your feed water and so if there's air air bubbles within the the feed water or oxygen and the reason is because it can cause internal corrosion within the boiler and your corrosion will start to corrode and that will create a lot of problems for you over time and so we use the aerating units in order to remove the oxygen from the feed water. So those are a couple of aspects of boilers. We have to be careful about the stack and sulfuric acid formation as well as oxygen in the feed water. So the next thing we're going to move on to we're going to take a look at turbines which is the next stage after the boiler.