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00:04:670Anna Stoppato: Okay, I will,
00:09:340Anna Stoppato: Okay, I, I loaded the slides of today. I'm… even if I will write, so later I will load also the slides after my additional,
00:22:790Anna Stoppato: Do you trust that?
00:24:30Anna Stoppato: And, as a last thing, I forgot the last week, I don't know why, but, today I will, add also the lesson of, last, Thursday. No, yes, Thursday, we have a lesson on Thursday.
00:37:620Anna Stoppato: Okay, so… Very, very quickly today, something related to the use of hydrogen in gas turbine.
00:45:870Anna Stoppato: As a first, thing, why in gas turbine? We already talked about all the benefits related, related to fuel cells, which can produce, electricity, of course, also gas turbine, produce electricity. Of course, the main big,
01:05:700Anna Stoppato: So the benefits of gas starving are related to their diffusion.
01:10:930Anna Stoppato: They are a well-known technology.
01:14:110Anna Stoppato: They can have very large sizes, and you know that the power density of gas turbine is the highest among all the…
01:26:570Anna Stoppato: Possible, thermal power plant, Of course, sir.
01:34:240Anna Stoppato: We know that fuel cells can reach, or will reach, higher efficiencies, but we know that they are suitable for small sizes. Of course, as we have said, we can use modular solutions, but we need a lot of space. Well, for gas turbine.
01:53:90Anna Stoppato: The density of power is very, very higher.
01:57:660Anna Stoppato: They are a well-known technology, and yes, their efficiency, their theoretical efficiency is lower, but we know that we can also use the solution in combined cycle, where the efficiency
02:11:560Anna Stoppato: Is not, on… is the subject, of course, of, of the… cannot, limit, but, can reach 60.
02:23:40Anna Stoppato: Or more percent, and in the future, if we are able to increase the temperature, we can… the idea is to be able to reach 70%.
02:33:540Anna Stoppato: So, this is why many, many companies are working on the possibility to…
02:41:300Anna Stoppato: To load… to transform their already existing gas turbine into machines able to work with hydrogen, or to build, but probably this in the future, new machines designed for hydrogen.
02:59:280Anna Stoppato: Now, very, very quickly, on the theoretical point of view.
03:03:650Anna Stoppato: You know that, the Gastarbing works on the…
03:14:160Anna Stoppato: Sorry?
03:15:670Anna Stoppato: Okay. I started now, I did a… the first page was only the title.
03:20:770Anna Stoppato: So, I have only, sorry, one before going on? No, it is recording, yes.
03:27:360Anna Stoppato: I want to be sure.
03:30:720Anna Stoppato: So do you…
03:35:20Anna Stoppato: Because…
03:36:880Anna Stoppato: This time, it was not recording. Okay, so I only started to write this one. This is the very simple gas starving. Of course, now I start with this. You know that it is possible to transform this cycle into a combined cycle. The idea is that… and again, now I…
03:57:700Anna Stoppato: I start, but only to have an idea. This is the possible cycle.
04:05:370Anna Stoppato: Okay, on the TS diagram, with the point 1, to… 3 or 4 up…
04:17:760Anna Stoppato: Okay, the idea is why we cannot replace… usually these machines works on, with, using natural gas. They need, cleaner and…
04:29:280Anna Stoppato: liquid, but mainly gas fuel. Why don't replace this methane directly, or this natural gas directly, with hydrogen?
04:38:920Anna Stoppato: And this is the idea. On the theoretical point of view, everything is simple, but now we will see where are the points that should be…
04:51:730Anna Stoppato: or are going to be solved. Before that, we can replace, without any problem, Nathan with natural gas. I only remind you this equation, which is the same that we've already seen. The…
05:07:970Anna Stoppato: Combustion.
05:10:880Anna Stoppato: of hydrogen.
05:13:10Anna Stoppato: is made one molecule of hydrogen with half molecule of oxygen, becomes water. So again,
05:24:520Anna Stoppato: Of course, we know this because this is the subject of this course. The main idea is that using, hydrogen instead of oxygen, we can, completely decarbonize. We have seen this,
05:37:670Anna Stoppato: This, same reaction.
05:40:360Anna Stoppato: also in the fuel cells, but now, the difference is that in the previous case, we used directly this reaction to produce electricity. Now, the energy which is related by this reaction, which is a combustion, so now we have a flame, the energy is given to
06:04:720Anna Stoppato: A gas, air, or the flue gases, so it translates… it is transformed into thermal energy, and then the thermal energy, or the energy of 0.3, will be transformed into mechanical energy, rotation of the shaft, in the gas turbine.
06:22:760Anna Stoppato: Okay, now, what are the problems? So sorry, I hope that I can do it this way.
06:29:430Anna Stoppato: These are the main points, now we will see one by one, where we need to put the tension when we want, as I told you, to retrofit an old and existing
06:40:940Anna Stoppato: which usually was designed to work with natural gas, or when we… so, and we want to transform it into a machine able to work with hydrogen, or, as we will see, with the blends of hydrogen and natural gas.
06:58:740Anna Stoppato: Or, when we want to transform completely the machine to a new design suitable for hydrogen. In this picture, you can see there is the heat recovery steam generator, so this is a picture which already takes into consideration
07:15:520Anna Stoppato: the combined cycle gas turbine, but many of these things are valid also for single cycle gas turbine. The first point, the first on which we start, is related to the combustion system. Of course, it is clear the main topic, the main… the point where we introduce hydrogen is in the combustion chamber, so…
07:40:130Anna Stoppato: We need that to, analyze this. This is,
07:46:10Anna Stoppato: One important picture, we already, see it, which compare, on the point of view of the low heating value, metron, and, gas power. Gas power is natural gas, it is called gas power, because this is the name, which is used in the…
08:03:610Anna Stoppato: Darbinser?
08:05:100Anna Stoppato: Already, we already know the difference is the…
08:10:620Anna Stoppato: The great difference is, if we evaluate per mass heating value, of course, gas…
08:18:00Anna Stoppato: Sorry, gas power is hydrogen, sorry. I made an error. This is hydrogen. Hydrogen is,
08:27:320Anna Stoppato: 2.5 times the low eating value per mass basis than metron, but if we look to the volume basis, it is less than 1 third. And we know, and this is important, then we will see also other aspects, that
08:44:450Anna Stoppato: When we, design, all the elements, the flow passage areas and so on, they are more related to the volumetric flow than to the mass flow.
08:57:850Anna Stoppato: I don't remind if I… no, I need to add in this picture. I added here for you, but this is important, if we put together, of course, from… now I don't ask you to do this.
09:11:860Anna Stoppato: But from this picture, it is clear, comparing the LHV per volume and per mass basis, we can also find the density of the fluid. I remind you that when dealing with burners, one important parameter that has to be taken into consideration is the VAB index.
09:32:350Anna Stoppato: Which is defined. In this case, they… Don't use the hype…
09:38:890Anna Stoppato: But the low heating value over the square root of the,
09:46:540Anna Stoppato: relative density, which is the density of the fuel, with respect to the air. Two fuels of different composition, which has the same VBA index, can be managed by the same
10:02:340Anna Stoppato: Borners by the same, noddress and so on, so…
10:06:390Anna Stoppato: Because they are with the same volumetric flow rate, they transport the same energy. But if we calculate, for the meter and the Webe index is 53.28, these are megajoules over cubic meter, for the hydrogen is around 48
10:33:20Anna Stoppato: Okay? So, this is the first aspect that has to be taken into consideration. It is clear that if we want to replace methane with hydrogen, we need to resize the,
10:52:910Anna Stoppato: All the… all the parts, the burners, we have to replace the noddress, and so on, because we need more.
11:05:730Anna Stoppato: more area. We have to resize, we have to have greater elements, because we have, for the same energy rate, for the same power, for the same energy flow, we need more…
11:20:210Anna Stoppato: more volume. And this is the first aspect. If you want, again, if we look to the DSL, we have also to consider which is the ratio between oxygen and,
11:35:520Anna Stoppato: If you will. I write, I go back in the previous slide, I add also the equation related to, meter.
12:01:120Anna Stoppato: Okay, it is, clear that also the content of, oxygen is different for the two cases. For each molecular of hydrogen, we need half molecule of oxygen, and for one molecule of mutton.
12:18:730Anna Stoppato: We need 2 molecules of hydrogen. So, on the volumetric point of view,
12:26:00Anna Stoppato: we need less oxygen for hydrogen than for me. But if we look to the mass, so on.
12:38:880Anna Stoppato: Mas bezice.
12:44:220Anna Stoppato: For the first, we need,
12:48:980Anna Stoppato: more or less. 8. The ratio is 1 eighth.
13:00:270Anna Stoppato: So, it is…
13:06:970Anna Stoppato: So it means that for each kilogram of metron, we need 8 kilograms of air.
13:19:300Anna Stoppato: For the metan, it's 1… 4.
13:25:340Anna Stoppato: This is with the oxygen. If we want to… if we take into consideration that, presently, the, usually the,
13:37:700Anna Stoppato: We don't use pure oxygen, but we use air.
13:42:560Anna Stoppato: So, considering air, the ratio for hydrogen becomes… sorry, I don't know what moves, okay? No.
13:52:920Anna Stoppato: No, sorry, Mickey.
13:55:600Anna Stoppato: Okay, for air, this, become… for hydrogen is 1 over 24.5. These are kilograms of air over kilograms per kilogram of hydrogen, while for,
14:13:490Anna Stoppato: Meatan is… 1 over, 60.2.
14:27:690Anna Stoppato: Okay, so there is a difference, and we have to take into consideration also this, so we don't have only to re… To consider that we need a different amount of fuel, and as I told you, the difference is both on mass basis and volume basis, but when we have to size something…
14:47:150Anna Stoppato: The volumetric flow rate is most important, but also we have to
14:52:60Anna Stoppato: Take into consideration that we have also to take… we have… we need a different amount of air.
14:58:730Anna Stoppato: Because, of course, the reaction is different. So this is the first important difference that we have for the combustion, and also for all the elements that are before the combustion chamber, the elements that take hydrogen and take air and put, and take hydrogen, sorry.
15:20:410Anna Stoppato: And put it inside the combustion chamber.
15:23:550Anna Stoppato: There is also… oh, sorry, here. Here, we are… there are other parameters which are important when, we have to…
15:36:470Anna Stoppato: design the combustion chamber. Okay, the first important is the adiabatic flame temperature.
15:46:190Anna Stoppato: Okay, and you can see that there are two different, so the adiabatic temperature flame of hydrogen is higher than the adiabatic flame temperature of metan. The difference is about, of course.
16:05:390Anna Stoppato: the values can be a little different for the meter, because sometimes you know that, like,
16:11:470Anna Stoppato: We write metan, but it is natural gas, whose composition can be a little bit different.
16:19:100Anna Stoppato: But in any case, the difference is important. And this difference makes, or gives us, two different problems. The first is related to the materials, because, of course, if the temperatures are higher, we need to…
16:35:790Anna Stoppato: have materials which are able to work at higher temperature, or… and now we will see the other aspect, or we need to dilute the product, the…
16:48:50Anna Stoppato: The product of reaction in order to decrease the temperature. And there is also another important aspect, which is related to the production of anoics.
16:59:910Anna Stoppato: You know that anoics is a problem, not because other nitrogen is present inside the fuel, but because nitrogen is present inside the air. And now, sorry, I hope that here I have some…
17:14:130Anna Stoppato: Pirate, okay. These are two simple pills, sorry.
17:19:770Anna Stoppato: picture, and if we go to the picture on the left, there is the production of an oxid,
17:32:980Anna Stoppato: at different value of the flame temperature. And you can see that the other is the equivalence ratio. One means that we are working in stoichiometric conditions, so with the quantity of oxygen, which is exactly the stoichiometric one.
17:49:90Anna Stoppato: So… Of course, we have already seen, which is the ratio between a hydrogen… which… between…
17:57:590Anna Stoppato: Oxygen, air, and fuel, depends on the fuel.
18:01:820Anna Stoppato: On the left, we have lean mixers, so it means that the oxygen is lower than the stoichiometric one. Sorry, is higher, sorry. On the other side, we have rich, so it means that we are working with the…
18:21:910Anna Stoppato: more fuel than, the stoichiometric one. You know that, we can, work in two different, places. The…
18:33:710Anna Stoppato: More traditional, the older one, is in the orange area, which is related to the diffusion flame.
18:41:750Anna Stoppato: So we are working close to the stoichiometric value, so the ratio between air and the fuel is close to the stoichiometric value. Of course, the flame is stable.
18:57:420Anna Stoppato: We reach the highest temperature, but this is also the point where we have the maximum production of anoics.
19:06:470Anna Stoppato: This is the typical diffusion, combustion chamber.
19:11:960Anna Stoppato: If you will enter, The air is this green, and here we have the flame.
19:21:800Anna Stoppato: We can also use the limb premixed flame.
19:27:320Anna Stoppato: air, fuel, and air enter together. These are very simple representations, but these are the ones which are
19:36:100Anna Stoppato: more general, because you know that then each,
19:40:960Anna Stoppato: Each company has its own specific geometry, but the idea is this one. Air and fuel are mixed together before the flame, so when they arrive here, here we have the flame, they are.
19:56:710Anna Stoppato: Well, mix it together.
19:59:810Anna Stoppato: Okay, which is the great advantage of this combustion, is that we work in this position, so with lower temperature, and also lower production of anoics.
20:13:860Anna Stoppato: In the new… Combustion chambers in the new… of the new…
20:22:30Anna Stoppato: New means in the last 20 years, and nowadays, the gas starving works usually in this part.
20:30:430Anna Stoppato: The so-called dry low and ox works, work there.
20:37:300Anna Stoppato: you know that… okay, we're already in… okay.
20:41:830Anna Stoppato: Which is the problem of hydrogen. If we go back, you have to see also another important problem.
20:49:330Anna Stoppato: difference between metron and hydrogen, I think that you know, which is the different flame speed. You can see that for metan, it's about 0.3, 0.4 meter per second.
21:02:720Anna Stoppato: For the hydrogen is 2, 3, so it is more or less 10 times higher, 2, 3 meters per second.
21:13:420Anna Stoppato: Okay, this big difference makes impossible the use of this kind of
21:21:430Anna Stoppato: combustion. Why? Because we can have… So…
21:27:390Anna Stoppato: a propagation of the flame, so the velocity of the flame is higher than the velocity of the fuel and the air, which exit and enter the combustion chamber. So, we can have the problem of…
21:42:530Anna Stoppato: The propagation upstream inside the premixed nodule of the flame.
21:51:350Anna Stoppato: This can produce many problems in the premixed nodule, which is not designed in order to have the flame. It is designed, of course, for high temperature, but not for the temperature of the…
22:05:380Anna Stoppato: Of the flame itself, and also remind that,
22:09:960Anna Stoppato: We have an increase… the geometry is made… take into consideration that when we have the combustion, also the density of the…
22:23:170Anna Stoppato: air of the gas increases, so the geometry is made in order to take into consideration this aspect. If we have the flame in a place where it is not planted.
22:35:370Anna Stoppato: We can have also problems related to pressures and to mechanical stresses.
22:40:780Anna Stoppato: Okay.
22:41:810Anna Stoppato: Sometimes we can have problems also of flashback, so it is possible that the flame arrives here, then it is not able to be stabilized, and so it moves again toward the premix, through the…
22:58:140Anna Stoppato: correct the zone and combat, you know, we can have a movement of the flame.
23:04:160Anna Stoppato: We have problems, both if we have this movement.
23:08:340Anna Stoppato: But also if the frame is able to stabilize also here.
23:14:00Anna Stoppato: Of course, in some cases, we can have also the problem that the flamer can also go…
23:20:480Anna Stoppato: Before the premixel module, and here we can have also problems of,
23:26:930Anna Stoppato: of Safity. In any case, this kind of combustion is not possible when we use hydrogen. Now, many people are working.
23:38:150Anna Stoppato: But, to have an idea, actually, we can admit.
23:44:340Anna Stoppato: at maximum between 15 and 30% in volume of hydrogen, okay, to use this kind of combustion. So, between 15 and 30. Of course, the range is big, but of course, there are also many different machines and many different technologies.
24:04:160Anna Stoppato: If we want, at present, to have an increased amount of hydrogen inside the fuel, we need to pass to this kind of solution.
24:16:270Anna Stoppato: Of course, which is the problem? Okay, so this is,
24:20:340Anna Stoppato: Okay, what I said, and here, okay, sorry, here it was general.
24:27:250Anna Stoppato: It is mainly related to the content of hydrogen in fuel, and to the increase of anoics, but as I told you, the problem is related to what I said to you. Okay,
24:41:230Anna Stoppato: So this is later.
24:43:250Anna Stoppato: Okay. What? It is possible that,
24:48:940Anna Stoppato: We do, with this, and I know I go back here.
24:55:120Anna Stoppato: Okay.
24:56:580Anna Stoppato: one possibility that we have is the addition of a selective catalytic reduction. So, usually, I say usually, we don't need to treat the flue gases after the combustion. So, generally.
25:15:270Anna Stoppato: And now, I will explain better this word generally, but generally speaking.
25:21:370Anna Stoppato: we don't need. So, the dry low anoics combustor are good enough to permit to reach the limits, the low limits, for the production of anoics.
25:34:60Anna Stoppato: With hydrogen, generally, we need the use of… if we want to use Pure hydrogen, or…
25:43:620Anna Stoppato: high content of hydrogen, we need the use of this selective catalytic reduction, which is, you can see more or less, it is put here, because usually it needs to work to a temperature which are around 300, 350 degrees, so if we have a heat recovery steam generator, this element is in between, generally before the
26:08:610Anna Stoppato: economizers.
26:09:930Anna Stoppato: Okay, so…
26:12:200Anna Stoppato: So, the flue gases enter the heat recovery steam generators in a point where they have more or less 300 degrees, they exit, they go inside this selective catalytic reductor.
26:26:150Anna Stoppato: Then they come back and continuous the last part of the heat exchange inside the heat recovery steam generator.
26:34:680Anna Stoppato: This is one solution.
26:36:590Anna Stoppato: If we had this element also using natural gas, for example, because we were asked to do this, because the low limits are very, very restrictive in some
26:50:760Anna Stoppato: in some area.
26:52:450Anna Stoppato: in order to have the permission to build the plant, sometimes we are required to very… to guarantee very, very strictly value of anoics. Generally speaking, this, element is not sufficient.
27:08:890Anna Stoppato: If we use hydrogen. So, even if we have the use of natural gas, we need to increase… to enlarge it, if we want to use hydrogen. Note that sometimes,
27:22:830Anna Stoppato: And again, we are speaking about already existing turbines. When we use hydrogen, sometimes we do what is called de-rating, so we use the turbine with lower… at lower power, in order to reduce the production of anoics.
27:38:900Anna Stoppato: And again, this depends on the limits that were given during the building of the… Of the…
27:46:150Anna Stoppato: of the plant. So, these are the two, points, Okay,
27:54:620Anna Stoppato: Okay, another thing which is, often made up is that of, the fuel. The fuel is dealt with by
28:07:340Anna Stoppato: something which does not participate to the combustion. Note that this dilution must be given in the fuel itself, not later after the combustion, but before the combustion, we can put inside the hydrogen some elements, which are natural with respect to the
28:27:190Anna Stoppato: reaction. They can be ore, water, or steam.
28:31:690Anna Stoppato: Sometimes we use nitrogen. It seems strange that we use nitrogen, so we increase the content of nitrogen in order to reduce the emission of anoics, but the main mechanism is the decrease of the temperature. So even if we increase the content of nitrogen.
28:53:510Anna Stoppato: the production of NOX decreases, because we are able to decrease the value of the…
28:59:680Anna Stoppato: Of the temperature. So, this is, the second element, so…
29:06:170Anna Stoppato: the problems related to the, combustion genre. Then…
29:13:210Anna Stoppato: What about the turbine? You can see, okay, but what about… Now, we have the problems during the combustion.
29:21:510Anna Stoppato: which can be the problems related to the gas turbine. There are…
29:29:820Anna Stoppato: three problems, if we can't see. The first is related to the temperature. It is possible that the inlet temperature of the flue gases is higher
29:41:50Anna Stoppato: when we burn hydrogen than when we use natural gas. So, we have to take into consideration the problem related to the high temperature, but there is an additional problem
29:53:620Anna Stoppato: Which is together with this one. Which is related to the fuel gases, because the gas turbine, usually, is designed for the traditional composition of the fuel… of the gases, so…
30:09:540Anna Stoppato: We have, okay, a large quantity of nitrogen, if we use air, but then we have carbon dioxide, we have water.
30:19:380Anna Stoppato: If we burn hydrogen, we have only water, we have only steam, and of course, the characteristics of steam are different from the characteristics of fuel gas, which are the main differences. The first difference is,
30:38:430Anna Stoppato: Which is related to this, is related to the, heat exchange coefficient between the flu gases And they…
30:50:790Anna Stoppato: Materials, the world materials.
30:53:170Anna Stoppato: Wall means the case of the gas turbine, but also the blades of the turbine itself.
30:59:610Anna Stoppato: Generally speaking, the heat exchange, when we have only steam.
31:06:510Anna Stoppato: Okay, or better, only steam and nitrogen is higher than the heat exchange coefficient that we have traditionally. It means that even if the flue gas at the same temperature of the flue gases
31:22:560Anna Stoppato: They exchange more thermal energy with the blades, so the temperature of the blades increases.
31:29:110Anna Stoppato: Okay, so the problem of cooling is more important.
31:35:40Anna Stoppato: And, again, we have to take into consideration that all the cooling system, you know that the steam tar… sorry, the gas turbine are cooled, okay, traditional, but the cooling system usually is designed, taking into consideration
31:56:80Anna Stoppato: normal composition of the flue gases. So, again…
32:01:270Anna Stoppato: It is necessary to… probably to re-design, or we decrease the temperature, okay, with a large dilution of the fuel gases, or…
32:15:900Anna Stoppato: It is important to resize, redesign, also the cooling system of the gas turbine, since the composition of the flue gases is different, taking into consideration that this is important, and
32:29:620Anna Stoppato: I add that this problem becomes also a problem, or a challenge, also when we have a heat recovery steam generator after the gas charming, because again.
32:42:390Anna Stoppato: The flue gases have a different exchange coefficient, has a different…
32:49:70Anna Stoppato: specific heat. So, all data exchanges works in a different… work in a different way. So, again, if we use a heat recovery steam generator, which was designed
33:03:890Anna Stoppato: For etta, I've been working with Mita.
33:07:80Anna Stoppato: Probably, it doesn't work properly.
33:11:160Anna Stoppato: Okay, so…
33:12:200Anna Stoppato: Of course, it can work, but probably it is not optimized, so we need, again, especially in the future, we need to redesign all the systems.
33:23:360Anna Stoppato: I add also an additional aspect, which is related to the water itself, is also more corrosive, so the flue gases, when we burn hydrogen, are more corrosive than the flue gases when we burn natural gas.
33:42:730Anna Stoppato: So, again, it is important to be sure to control that the material of the blades is suitable.
33:51:740Anna Stoppato: For flu gas is very rich in water.
33:55:300Anna Stoppato: Of course, there are elements that are able to work with this, but it is important that…
34:01:300Anna Stoppato: We are sure, so…
34:03:60Anna Stoppato: Again, we need it. Usually, for example, we need alloys with nickel, okay, inside the…
34:10:980Anna Stoppato: Okay. And so this is, the…
34:15:860Anna Stoppato: The la- the… what is related to the gas charity.
34:19:840Anna Stoppato: Dan, sorry.
34:22:290Anna Stoppato: Okay, I don't remind… yes, this picture. Okay. And then a last aspect, now I need, yes, this. Again,
34:33:920Anna Stoppato: We have a turbine, so we have seen which problems can we have with the turbine, but we can have also a problem in the matching between the compressor and the turbine.
34:45:199Anna Stoppato: Why? Because, again, okay, the compressor compresses air, as in traditional gas turbine, but in the…
34:55:120Anna Stoppato: In gas starving, we have a few gases with a different composition, than,
35:02:780Anna Stoppato: The, traditional composition.
35:05:960Anna Stoppato: And also with the flow rate, which is different.
35:10:660Anna Stoppato: Because, of course, if we look to the mass, okay, we consider the mass of air and the mass of flow gases, and generally speaking, our diagrams, when we do the matching between compressor and turbine, are on…
35:26:500Anna Stoppato: Based on the mass, it is clear that we need less
35:33:780Anna Stoppato: Mass, then… so the addition of hydrogen, sorry.
35:39:800Anna Stoppato: the mass of the hydrogen is lower than the mass of natural gas. So the difference between… you know that the mass of the compressor and the mass of… the mass flow of the compressor and the mass flow of the turbine are not equal.
35:56:250Anna Stoppato: Because in the turbine, we have the addition of the fuel. Okay, so when we shape up… so, I remind you, this kind of…
36:06:90Anna Stoppato: Grafa.
36:07:530Anna Stoppato: When we put air the mass of air.
36:11:870Anna Stoppato: And they are the compression ratio. An image that this is… these are the different…
36:20:210Anna Stoppato: cores of the compressor for different values of,
36:25:100Anna Stoppato: So that we go… this is more vertical.
36:29:40Anna Stoppato: Okay, these are for different values, for example, of the valves opening.
36:34:730Anna Stoppato: And this is image that… this is the curve.
36:38:800Anna Stoppato: Of the turbine. So imagine that this is central is the reference, okay?
36:49:220Anna Stoppato: If we use hydrogen, for example, this core can become this one.
36:56:460Anna Stoppato: And so, the matching point… now I have a… okay. Of course, the difference between the two cores depends on…
37:04:300Anna Stoppato: how much hydrogen we are using, but imagine that, We are using pure hydrogen.
37:12:490Anna Stoppato: And we use the same rotational speed and the same opening of the valve. The design point moves on the curve.
37:24:90Anna Stoppato: So it is clear, again… That we have different points of operation.
37:31:880Anna Stoppato: There is also the risk, again, we need to be sure, that the point, the points approach the surge
37:41:700Anna Stoppato: Area, so the area where we can…
37:44:980Anna Stoppato: Could have problem of surge of the compressor, okay?
37:48:920Anna Stoppato: Of course, it is clear that if we see that for the specific gas starving, this point becomes too close to the surge, it means that this starving is not, absolutely not suitable to be converted. But it is clear that, again, we have to take into consideration
38:06:770Anna Stoppato: That we are using a different, a different,
38:11:860Anna Stoppato: a different fuel. And so this is very important, because it is clear that
38:17:460Anna Stoppato: there is the design of the machine, but there is also the control of the machines during the operation. So, especially if we want a flexibility in the machine, so that the same machine is able to work with different fuels.
38:32:240Anna Stoppato: We need to implement different, sometimes different, control strategies.
38:37:750Anna Stoppato: Depending on which.
38:40:540Anna Stoppato: fuel is used. So, for example, sometimes when we use hydrogen, we come a little bit close the
38:49:690Anna Stoppato: Inlet valves.
38:51:880Anna Stoppato: or we can operate changing the temperature. In any case, this is important.
38:59:420Anna Stoppato: Even if we… it seems that we operate only in the combustion chamber.
39:06:200Anna Stoppato: There is a difference also in the operation of the gas turbin.
39:10:00Anna Stoppato: And so, as usual… so, again,
39:15:710Anna Stoppato: Probably starting from now, new machines will be built.
39:20:220Anna Stoppato: With a design which was…
39:22:810Anna Stoppato: design it, which is directly for the use of rich… of fuel rich in hydrogen. For the other machines, sometimes this movement from this point to this point can be too much, so…
39:35:720Anna Stoppato: Again, we have seen other possible limits, but sometimes, also, the operational limit of the gas turbine can be a problem related to them.
39:45:670Anna Stoppato: To the operation.
39:48:220Anna Stoppato: Dan, okay, I want to go back again here, sorry.
39:56:160Anna Stoppato: Here. And, we'll look to another difference between beta and hydrogen, which is the flammability limits
40:08:30Anna Stoppato: And you can see that there is a very big difference. So, Mitan.
40:14:470Anna Stoppato: The limits are between 5… 5.217.
40:20:340Anna Stoppato: For the hydrogen, from 4 to 75.
40:25:840Anna Stoppato: And this is, again, This, again, add problems related to the Safity. Problems
40:34:590Anna Stoppato: Both related to the machine itself. So, for example, now I'll come back here. So, for example, you can…
40:43:200Anna Stoppato: See, the other big element on which we have to work, huh?
40:49:510Anna Stoppato: Which is the ventilation, the Zardos gas detection, and so on. So, inside the machine, we must be sure that never we reach this
41:01:410Anna Stoppato: ratio between fuel and air, but you can see that, of course, we have the same problem with the meter, but these limits are very narrow with respect to this, so it is
41:12:910Anna Stoppato: Easier.
41:14:960Anna Stoppato: to be outside this limit than to be outside this limit. So this can be a problem, and this needs especially attention during the startup and the shutdown phases.
41:27:540Anna Stoppato: Okay, so when the flame is not stable, where we start, or when we finish to operate, we should be sure that there is not any
41:43:60Anna Stoppato: hydrogen content in any part of the machine when there is not a flame. So, because it is clear that, for example, during the shutdown.
41:55:390Anna Stoppato: If we don't pay attention, it is possible that a last very small quantity of hydrogen enter inside the combustion chamber, but the flame is not working. It was already switched off.
42:11:660Anna Stoppato: But there is a very small quantity of hydrogen, and this very small quantity of hydrogen can also move inside the machine if the machine is not operating.
42:23:560Anna Stoppato: It is possible that somewhere… It reached this… composition.
42:31:900Anna Stoppato: And there is another… okay, now I didn't, yes, I have the number, I don't have the specific number, yes, I have…
42:41:290Anna Stoppato: Sorry, I forgot to put the page. But there is also an additional aspect, yes, which is the energy of ignition for hydrogen, which is very, very small. So what does it mean? It means that with only a very, very small amount of energy.
43:03:200Anna Stoppato: The hydrogen in air inside this very large composition.
43:10:180Anna Stoppato: Ken.
43:13:520Anna Stoppato: can be ignited. And this is really a problem. So, again, we have to take into consideration also the aspect related to Safity.
43:27:440Anna Stoppato: Okay, as I told you, mainly during startup and shutdown, because
43:33:860Anna Stoppato: Also, the very small energy of ignition. We can have a very small spark somewhere, a very small hot point somewhere, which starts the combustion.
43:46:680Anna Stoppato: Of course, the safeti problems can be also in other parts of the plant. We didn't mention, but we have to take into consideration that if we come back to the reason why we need to use the hydrogen.
44:01:930Anna Stoppato: it is easier to think that we can have… that we need a storage of hydrogen, okay? Because I remind you that
44:11:910Anna Stoppato: We want to transform renewable energy sources when
44:17:40Anna Stoppato: there is a peak in the production into hydrogen, and then use hydrogen when we need electricity. So this moving in time between the production and the use of hydrogen means that we need storage.
44:33:390Anna Stoppato: It is clear that if we need a storage near the gas turbine, we put an additional element of risk.
44:43:970Anna Stoppato: of danger.
44:45:980Anna Stoppato: So again, we are less,
44:50:190Anna Stoppato: So, these are more problems related to our colleagues, which work engineers, but it is clear that when you deal with large plants, to have an additional element of risk, for example, an area where people cannot work or cannot pass, because it is dangerous.
45:10:70Anna Stoppato: Make additional problem in the management of the plant, not of the strictly operation of the gas-starving, but…
45:19:820Anna Stoppato: we can have problems for the maintenance and so on. So, again, these are all problems. Some of them are well known.
45:27:830Anna Stoppato: But again, it is completely different when we…
45:32:290Anna Stoppato: Are using hydrogen in a lab, in a small turbine, only for, ex…
45:38:820Anna Stoppato: As a pilot plant, or when we want to translate into commercial plants.
45:44:770Anna Stoppato: Okay? The same solution that…
45:48:900Anna Stoppato: are acceptable for pilot plants, usually are not acceptable for commercial plants, because they are expensive. If we have a turbine of 1 megawatt.
45:59:790Anna Stoppato: Okay, you can also store a tank of hydrogen, but…
46:04:810Anna Stoppato: We have problems, but in a small volume. If we want to have a plant with 1,000 megawatts.
46:17:30Anna Stoppato: tank of hydrogen is empty…
46:20:990Anna Stoppato: 1,000 times larger, so the problem becomes very, very large. So, these are all the problems. I hope to have saved something, but now okay.
46:32:460Anna Stoppato: Okay, yes. And then, a last problem, but again, it is an important… so, it is again in this, sorry, in this,
46:43:790Anna Stoppato: part… this part… one, also, better, two problems. One, which is related to the gas… generally speaking, to the gas turbine, but also to the heat recovery steam generator, if… if we have, again, the problem related to materials. I spoke,
47:00:460Anna Stoppato: Of the problems related to the high temperatures in the gas turbine. But, you know, also another important problem, which is related to the…
47:09:620Anna Stoppato: Use of hydrogen whose molecule is so small that it can enter in some
47:19:40Anna Stoppato: crystalline reticulus of some materials with the so-called embritlement of materials, which makes them very fragile. So, again, if we have hydrogen,
47:34:260Anna Stoppato: It is possible that we need to use different material, especially for the seamless. Okay.
47:40:990Anna Stoppato: So this is very important, but a last, importance is the last, this gas detection.
47:48:750Anna Stoppato: you know that in every plant, there are some instrumentations which, not only for hydrogen, which detect possible leakages of fuels. We have them for natural gas.
48:02:120Anna Stoppato: Of course, we have them for hydrogen. Usually speaking, the same detector, which are used for metan.
48:10:920Anna Stoppato: are not valid for hydrogen, so…
48:14:970Anna Stoppato: It is needed, again, to change all the detectors, or many of the detectors. Note that the flame of hydrogen is not invisible, but its lumiosity is very, very small with respect to the flame of Miton.
48:34:260Anna Stoppato: So, for example, all the detectors which are based on the flame cannot be used.
48:40:970Anna Stoppato: and that have been built for the flame of Mitan cannot be used for the flame of hydrogen, because it is not… it becomes invisible. So again.
48:53:690Anna Stoppato: Okay, you say to me, small things, yes, small things, but we have to take into consideration. Some of them are also expensive with respect to the…
49:04:310Anna Stoppato: the elements that are used for maintenance, or in any case, we need to change. If a plant is built to work with them.
49:14:610Anna Stoppato: meter has to change this. And now, the last two slides before a little bit different thing, are this one, okay?
49:27:800Anna Stoppato: At this one, because I think that they are important. There is the CO2 reduction, CO2 reduction, so the carbon reduction in the fuel gas, in the…
49:42:620Anna Stoppato: Blends between hydrogen and nitron.
49:47:570Anna Stoppato: If we look to this, the second one, it is clear that it is linear. The second one is based on the heat content. It is linear. So, if we replace one unit of energy of beetan with one unit of energy of
50:06:610Anna Stoppato: Hydrogen, we… Avoid it.
50:11:380Anna Stoppato: the mission of this one unit, so…
50:14:540Anna Stoppato: If we have 70% of, meter.
50:20:540Anna Stoppato: Okay, we have a reduction. Also, the emissions are 70%, okay? If we have, 20% of beta.
50:30:510Anna Stoppato: There, also there.
50:33:140Anna Stoppato: Emissions are 20%, so we reduce them.
50:36:810Anna Stoppato: of 80%. But generally speaking, and this is important, again, when we speak about blends, we refer to the volume.
50:47:30Anna Stoppato: So, when we say 30%, it means that we have 30% in volume of metron and 70% of volume of hydrogen. And this is very important. This curve is completely different, of course, because of the difference in the density, and of
51:07:300Anna Stoppato: And a little bit also in the heating value, but it is important. So, if we say that we have a blend of 50% of metan and 50% of it hydrogen, so we replace 50% of metan, you can see that the reduction of the emission is
51:25:170Anna Stoppato: 20%, not 50%, in order to have… For example, 50% of reduction.
51:34:460Anna Stoppato: We need 75% of hydrogen, 25% of metron.
51:40:10Anna Stoppato: Of course, we know these things, so we are not surprised, but it is clear that if we don't think about this.
51:50:540Anna Stoppato: We can also make errors when speaking with people, so be careful that when we speak about blends, we refer to the volume.
51:59:920Anna Stoppato: ratio, and this is the corrector.
52:05:550Anna Stoppato: So, we don't… If we want to…
52:10:280Anna Stoppato: As the emissions we need to put.
52:15:470Anna Stoppato: Around 25% of, metan and 75% of… Hydrogen?
52:24:00Anna Stoppato: And, again, this is, the same picture, this is the same picture. The other one is the so-called carbon intensity, and you know that it is the passage from the composites, from the content of carbon inside the flue gases, and, the,
52:44:640Anna Stoppato: Quantity of,
52:46:970Anna Stoppato: carbon dioxide per kilowatt hour, what we call the delta in the course of combined cycles. And again, so this is the core. So, again.
52:58:460Anna Stoppato: If we want to, of course, note that while the dark green one depends only on the fuel itself, the light green one depends on the efficiency of the machine, so it has been
53:15:50Anna Stoppato: drove not taken into account the normal,
53:19:670Anna Stoppato: The normal efficiency, the usual efficiency of the combined cycle nowadays.
53:27:170Anna Stoppato: while I show you, because, for example, this is the…
53:33:70Anna Stoppato: Okay, the European, european inter…
53:41:770Anna Stoppato: I don't know, okay, inter… no, no, it is not international, so, but the bank, because… why? Because they, said that, starting from now, or better, starting from some years ago, they gave, they give, money.
53:57:960Anna Stoppato: They, only, they lend money, money only if the, carbon emission intensity is lower than 250 grams per kilowatt hour. It is clear that it means that
54:15:420Anna Stoppato: If we want to have this benefit for our plant, if we want to use
54:23:310Anna Stoppato: Me done, we need to use at least 50% of hydrogen.
54:28:170Anna Stoppato: The annual… the actual emissions are about 330 grams per kilowatt hour.
54:34:250Anna Stoppato: Of carbon dioxide.
54:37:90Anna Stoppato: Okay.
54:38:280Anna Stoppato: And this is very important, okay?
54:42:130Anna Stoppato: Okay, so now… Okay, so did.
54:48:50Anna Stoppato: I put a lot of… Okay, so these are… this is what we are… doing now.
54:58:110Anna Stoppato: Sorry, I put there… I already show you in a different course, so it is not important that we look at there, but only to see here, for example, how some…
55:13:250Anna Stoppato: some,
55:18:150Anna Stoppato: company, building, gas turbine. This is CMS, this, but there is the same also for Ansaldo. They, give, as I told you, about 30% of maximum hydrogen production.
55:34:290Anna Stoppato: We can arrive with 100%, using wet, low, anoics emission burner, which means that we don't have premixed, but we deal with water.
55:49:10Anna Stoppato: the…
55:51:290Anna Stoppato: the fuel in order to reduce the emissions. But I already saw you, but only to say to you that, really, speaking now, the companies are working on this. What I want to show you… now I, I do with you the drover on the…
56:10:200Anna Stoppato: on the… on the sheet, I will add the official drawing, is a different, idea. What is this one? Okay. We use hydrogen instead of,
56:25:700Anna Stoppato: meter, and, okay, we have advantage. But can we, exploit in a different way
56:37:90Anna Stoppato: The consequence that we… our flue gases are water.
56:43:120Anna Stoppato: Water, of course, steamer.
56:46:200Anna Stoppato: And so there are some proposals. Now I show you some proposal of… Close cycles.
56:54:860Anna Stoppato: Of course, sir.
56:58:280Anna Stoppato: There are some projects on DSS, or there are some studies.
57:02:880Anna Stoppato: While for the hydrogen… for the traditional gas turbine working with hydrogen, we can find also commercially some machines.
57:13:670Anna Stoppato: These are only… Nor pilot. Lab.
57:19:530Anna Stoppato: or computer-based, cycles, but it is interesting to show to you. Now, I start… okay, the color is the same. Sorry.
57:31:200Anna Stoppato: Now, I will put with you also some number.
57:36:60Anna Stoppato: We, instead of having a… Open circuit, we have a closed one.
57:45:990Anna Stoppato: Sony,
57:51:40Anna Stoppato: Okay, so… and now, okay, I know that usually…
57:55:980Anna Stoppato: Well, it goes down only because it is easier.
58:09:380Anna Stoppato: Now it is a little more difficult.
58:14:650Anna Stoppato: Okay, this is a heat recovery steam generator.
58:26:950Anna Stoppato: Okay, so this is a compressor.
58:30:520Anna Stoppato: This is the combustion chamber.
58:35:440Anna Stoppato: And this is the gas derby.
58:41:530Anna Stoppato: Okay, in the combustion chamber, now I change the color. Enter. Hydrogen.
58:51:180Anna Stoppato: And, okay, I put the same color, but it is the same, and oxygen. So the idea is, instead of using,
59:00:460Anna Stoppato: Air, we use oxygen, in order to avoid the presence of nitrogen.
59:10:450Anna Stoppato: Okay, but now… and so we use, but now I don't finish the… now I, okay.
59:21:820Anna Stoppato: Okay.
59:23:320Anna Stoppato: This is it.
59:27:820Anna Stoppato: It recovers steam generator.
59:32:350Anna Stoppato: Now, it is a little bit difficult for me, okay.
59:41:870Anna Stoppato: Sorry, do it this way. Okay. Now, I know… usually we didn't draw this line, but it is only for me to remind you that we are using… okay.
59:56:30Anna Stoppato: We take in this point.
00:03:450Anna Stoppato: a drainer.
00:05:130Anna Stoppato: Okay? So this is a circuit of,
00:15:90Anna Stoppato: I write, but it is clear, hydrogen, oxygen, after the combustion chamber, we have water.
00:21:910Anna Stoppato: We take part of this water.
00:25:300Anna Stoppato: Now I will write with you also the number, and this water is sent to a… Steam turbine.
00:40:60Anna Stoppato: Then we have the condenser.
00:46:860Anna Stoppato: Then we have a pump.
00:54:450Anna Stoppato: Then, now, this is a simplified… we have one preheater, We did.
01:03:570Anna Stoppato: This is the official drawing.
01:07:470Anna Stoppato: Note that this is, okay, a cycle.
01:11:340Anna Stoppato: And then, this is the water.
01:16:110Anna Stoppato: We're just sun here?
01:18:680Anna Stoppato: Economizer.
01:22:530Anna Stoppato: Rum.
01:25:770Anna Stoppato: Evaporizer, sorry.
01:29:270Anna Stoppato: And,
01:37:780Anna Stoppato: Transparenter.
01:44:980Anna Stoppato: Then this water is taken here.
01:49:440Anna Stoppato: And is sent to another steam derby.
01:58:380Anna Stoppato: And then it is sent back here.
02:09:70Anna Stoppato: Okay, so it is clear that the same water
02:12:720Anna Stoppato: I missed the last element. I changed the color only to have in mind this. Here we have a valve at 3…
02:22:330Anna Stoppato: Okay, with the draining.
02:24:920Anna Stoppato: and disease.
02:27:420Anna Stoppato: Sandebecker.
02:33:580Anna Stoppato: and diseases.
02:39:30Anna Stoppato: lost, of course. Why we need… why we need a drain?
02:49:710Anna Stoppato: Of course, to compete, because… This is a closed circuit. Since it enters hydrogen and oxygen.
03:01:470Anna Stoppato: in order to maintain the balance of masses, we need to dream. Now, with you, we follow step-by-step everything.
03:16:230Anna Stoppato: If you want, with… when you have… so, I changed the colors, but… This is what?
03:26:580Anna Stoppato: Everywhere we have water.
03:30:490Anna Stoppato: Now, I say to you why I changed the colors.
03:34:270Anna Stoppato: So, also, this is water.
03:43:500Anna Stoppato: Nope.
03:45:810Anna Stoppato: why I changed the color? For two reasons. One is graphical, in order that we have in mind that we have a gas turbine.
03:56:400Anna Stoppato: And the steam cycle.
03:59:390Anna Stoppato: And, okay, the fluid is water.
04:03:80Anna Stoppato: In the red lines.
04:05:910Anna Stoppato: The characteristics of waters are such that we can consider this water as a gas.
04:14:280Anna Stoppato: In the… Blue? Light blue?
04:20:660Anna Stoppato: It is a vapor, or a liquid.
04:24:20Anna Stoppato: Okay?
04:25:800Anna Stoppato: Of course, we know that,
04:33:350Anna Stoppato: What does it mean? That in the red part, the fluid is…
04:38:750Anna Stoppato: consider a gas. It means that we are so far from the… Phase change occur over.
04:48:710Anna Stoppato: Okay? That we can consider the characteristic of the water close to the characteristic of a gas. For example, that the specific heat doesn't change with the temperature. We can consider it as constant, okay?
05:06:270Anna Stoppato: In the other part, we are closer inside the curve, and so the characteristics are the characteristic of a vapor, where, of course, we have to take into consideration that, for example, there is not a linear dependency of enthalpy from temperature, okay?
05:24:340Anna Stoppato: But the food is always the same. So, if you want, later I can… now I do, for example, starting from the combustion chamber. In the combustion chamber, the pressure is around 50 bars.
05:40:930Anna Stoppato: Okay, so here we have around 50 bars.
05:45:630Anna Stoppato: And after the combustion chamber, we have around 170… sorry… Yeah, 1700, Cassius degrees.
06:02:870Anna Stoppato: Only to have an idea. I'm sorry, I was… So it is here.
06:09:900Anna Stoppato: We are around in this point, Oli?
06:16:970Anna Stoppato: No, it is not. Okay. More or less in that point, okay?
06:21:610Anna Stoppato: It is clear, it is air, it is water, but…
06:26:920Anna Stoppato: We can consider it as a loss.
06:34:230Anna Stoppato: Then the expansion is more or less until 1.5 bars.
06:47:210Anna Stoppato: Of course, I give you these numbers, because these numbers were…
06:53:390Anna Stoppato: Were optimized for this kind of circuit.
06:58:190Anna Stoppato: Okay? It means, again, I made here,
07:05:430Anna Stoppato: We got the disease 1.5, and we arrive around here.
07:17:120Anna Stoppato: Yes, only to have an idea, more or less here.
07:23:280Anna Stoppato: So if this is point 1… And this is 0.2.
07:31:480Anna Stoppato: This is 0.1, and this is 0.2.
07:37:260Anna Stoppato: This temperature should be, sorry, probably… okay. Something like that.
07:43:740Anna Stoppato: Then, from point 2 and 0.3, we have there.
07:52:680Anna Stoppato: Isabatic.
07:54:320Anna Stoppato: Transformation, with a decrease of temperature, we arrive at a temperature which is more, something more than 100 degrees.
08:06:470Anna Stoppato: Peter Rice model, let's see… Europe?
08:16:670Anna Stoppato: Okay, this is 3.
08:19:569Anna Stoppato: And more or less, this is 4.
08:24:140Anna Stoppato: Okay.
08:32:670Anna Stoppato: So this is the red cycle.
08:36:390Anna Stoppato: Now,
08:39:29Anna Stoppato: you know that the lines are not perfectly vertical, but very close to vertical, okay? So 1, 2, 3, and 4.
08:52:979Anna Stoppato: I call this point, I'm not sorry.
08:59:130Anna Stoppato: I want to change here. If you want, we can call this point, dad, ne?
09:08:899Anna Stoppato: Point 10 is more or less here,
09:20:149Anna Stoppato: It's more or less here.
09:28:260Anna Stoppato: No, sorry, even a little bit… Here's… is here.
09:40:500Anna Stoppato: And then, we can consider…
09:43:439Anna Stoppato: From time, we have the expansion until point C. We have here, in their droving, they consider around 0.05 bars here.
10:03:580Anna Stoppato: No, sorry, no, no, I could… this is… this is worse than I, the last.
10:08:610Anna Stoppato: It's too late to… Then we have the condensation.
10:18:890Anna Stoppato: We are around ambient temperature.
10:28:830Anna Stoppato: C? This is C0?
10:42:60Anna Stoppato: Then the fluid is compressed now. Okay, there is the preheater and so on, but okay. The pressure here is around 150 bars.
10:58:420Anna Stoppato: Okay?
11:06:710Anna Stoppato: Okay.
11:07:920Anna Stoppato: And then here, of course, these numbers are very, very high, but they are supposed to arrive to 850 Celsius.
11:26:170Anna Stoppato: Okay… activity here.
11:30:360Anna Stoppato: And now, 800 is more or less… Europe?
11:37:540Anna Stoppato: Okay…
11:41:740Anna Stoppato: Sorry. So this is what happens. So this is the point, I don't know, call it, 11.
11:53:600Anna Stoppato: And this is 12.
11:58:340Anna Stoppato: 11 is here.
12:01:650Anna Stoppato: And 12 is… here.
12:08:470Anna Stoppato: Then we mix 12 and 4.
12:13:170Anna Stoppato: So, okay, the real point will start until later.
12:19:750Anna Stoppato: In their picture, they were not able to have 12 and 4E equal, but it is the same.
12:26:710Anna Stoppato: So this is the system. It is clear that the red works in the area where the fluid can be considered a gas.
12:37:420Anna Stoppato: Damn.
12:39:380Anna Stoppato: The blue one is in the area, sorry, I forgot to close this, of course.
12:44:780Anna Stoppato: Here, we have the pumps.
12:51:300Anna Stoppato: Sorry, this is not… sorry, this is…
13:01:160Anna Stoppato: Okay, this is only… these are the other… This is only to see, okay, we are walking here.
13:10:750Anna Stoppato: This is the best one. Okay, so this is, which is the advantage. The advantage is, that, with only one cycle.
13:20:740Anna Stoppato: We work between The highest temperature, which is 1700, And, ambient temperature.
13:32:660Anna Stoppato: which is around 30 degrees. So we are… we are… we have put together… we have an internal
13:42:920Anna Stoppato: combine its… Okay, so the heat recovery steam generator is internal.
13:48:980Anna Stoppato: And it permits us to have a better overall efficiency, because we are working Between two limits of temperature.
13:58:990Anna Stoppato: So… the… On the paper, deficiency of this plant can be higher than 73%.
14:14:570Anna Stoppato: Okay.
14:16:410Anna Stoppato: So very, very high.
14:18:280Anna Stoppato: Of course, and then, as I told you, we have a drain of water. Of course,
14:25:500Anna Stoppato: The quantity of water that we drain is exactly as the same mass than the mass of hydrogen oxygen that we put inside the combustion chamber, in order that the balance of masses is always constant.
14:39:840Anna Stoppato: Okay.
14:41:990Anna Stoppato: Of course, many problems. The first, it is clear, I gave you values which are very high of temperature. For example, for the steam turbine, I say U850.
14:56:500Anna Stoppato: It is very higher than traditional turbines. I remind you that in the steam circuit, we don't have the flame with all the problems related to the flames.
15:08:370Anna Stoppato: It is clear that this temperature is higher than the traditional temperatures that we have in steam power plants. I remind you that, generally speaking, we have the limit of 600 degrees.
15:21:80Anna Stoppato: But it is clear that now, if they want to do a… this improvement, this is the best thing that they can do. A second aspect, this is the efficiency of this cycle, but we have to take into account… into consideration one important thing.
15:41:210Anna Stoppato: Which is that we are using oxygen.
15:44:590Anna Stoppato: But we don't find oxygen.
15:48:390Anna Stoppato: as pure oxygen, of course.
15:52:860Anna Stoppato: Unless very short number of,
15:57:340Anna Stoppato: Oxygen as byproduct of other chemical processes. We need to produce oxygen starting from air, because we need to separate nitrogen from
16:08:320Anna Stoppato: Oxygen?
16:09:850Anna Stoppato: And so, yes, efficiency of this cycle is very, very high, but we have taken into consideration that to produce oxygen, we need to spend energy, because usually we produce oxygen starting from
16:24:570Anna Stoppato: Cryogenic processes.
16:27:260Anna Stoppato: So it is clear that this is not, so simple. There are other… so this is the most,
16:37:800Anna Stoppato: The one on which many people are working, also from companies, probably mainly because
16:44:770Anna Stoppato: If they are able to find a solution, probably with lower values of the thermodynamic parameters, it can be a good discover, but…
16:55:220Anna Stoppato: Another possibility is this one. We maintain the nitrogen with the oxygen. Of course, we have taken into consideration this. And…
17:06:170Anna Stoppato: Of course, with, large amount of nitrogen with moves, and so consider is also the characteristic of nitrogen.
17:18:140Anna Stoppato: We can separate it, when, water becomes liquid. So we need to have hydrogen inside with water, then, of course.
17:30:660Anna Stoppato: With different thermodynamics parameters, but we can separate later the nitrogen because, of course, we need to separate the nitrogen because it cannot stay inside the cycle, and we separate it working, arriving to temperature which are lower than
17:48:770Anna Stoppato: 100 degrees, working in ambient conditions, and then nitrogen exit, and water is liquid, and…
17:56:900Anna Stoppato: can be restored inside the circuit. Of course, this permits us to avoid the separation of oxygen from nitrogen, but add additional problems which are related to the management of this nitrogen inside the cycle itself. But…
18:15:190Anna Stoppato: This is, I think, nevertheless an interesting thing, because, okay, there is really this…
18:24:100Anna Stoppato: The challenge to find a new process, not to… since the hydrogen has different characteristics from… Meet done.
18:33:890Anna Stoppato: The challenge is not only to replace, is it a fuel, but trying, really, to think again to new possible cycles.
18:43:80Anna Stoppato: This is one of them. I didn't say to you, but only to have an idea, the… of course, as you have seen, part of the water
18:55:70Anna Stoppato: those… does the… Red circuit. Only part goes also in the steam turbine.
19:06:650Anna Stoppato: More or less, so this is, of course,
19:12:700Anna Stoppato: It is, sorry, around, 40%, okay?
19:20:710Anna Stoppato: So, 40% of the air goes in the blue circuit, and 60%.
19:32:270Anna Stoppato: Complete.
19:35:290Anna Stoppato: So… so note that until this point, we have all the water, then in this point, part is sent back to the compressor, part is sent back.
19:47:10Anna Stoppato: Okay.
19:48:340Anna Stoppato: It is clear that, Of course, this number… Can change depending on the…
19:57:290Anna Stoppato: the values of temperature and so on. It is clear that the… Part of water, which…
20:07:530Anna Stoppato: is in the blue circuit, so it's not compressed, but it is pumped. And you know the big difference between pumping and compressing.
20:17:90Anna Stoppato: Because the energy that we need to give in the compressor, it is many times…
20:23:80Anna Stoppato: many times means 100 times higher than the energy that we gave to the same amount of fluid if it is pumped, okay? It is close to 1,000, a little, in this case, a little less, but
20:39:480Anna Stoppato: Okay.
20:40:600Anna Stoppato: And this is very important. So, okay, we have to optimize in order, because, of course, we have to guarantee the equilibrium also in the heat recovery steam generator. But, okay, so…
20:51:860Anna Stoppato: This is the,
20:54:840Anna Stoppato: Okay, this is the last, picture. I will put you, the official one, also with the other numbers of pressure, of temperature, but, I think that this is very interesting. Only a last, last, thing that sometimes is noticed.
21:13:320Anna Stoppato: is that, of course, now coming back, because I forgot, but now I found this. Okay, now there is the CO2 reduction. Even when we burn hydrogen, there is a small content of carbon dioxide in the fuel gas.
21:32:860Anna Stoppato: Why? Because we have carbon dioxide in the air.
21:36:670Anna Stoppato: So when we take the air from the ambient, there is a small amount of carbon dioxide, some percent.
21:44:360Anna Stoppato: And, of course, even if we burn hydrogen, we find it…
21:50:590Anna Stoppato: Interview at the end of the…
21:54:190Anna Stoppato: So, of course, again, only to take into consideration, but this is important because, again, you can find sometimes people that said hydrogen is not able to reduce completely.
22:11:10Anna Stoppato: Be careful, because this content of carbon is related to something which already was in the atmosphere. We take and immediately send it back, and this is very important. And this is the same also for other kind of pollutants.
22:26:470Anna Stoppato: If there is some pollutant in the air, and it arrives at the end, we cannot allocate this pollution on the machine itself, because it only transported from the inlet to the outlet, but…
22:42:770Anna Stoppato: Which are very close, we can all… we can all say that we are moving…
22:47:880Anna Stoppato: pollution. Okay, very, very quickly, what about the use of hydrogen also in internal combustion engines? More or less.
22:58:440Anna Stoppato: even in that field, there are many studies, again, for the same reason. Internal combustion engines are well known, especially for transportation. We…
23:11:160Anna Stoppato: So, if it is possible to use them for hydrogen, so to decarbonize the transportation using the same kind of engine instead of replacing with the fuel cell, this can be very interesting. So, we have, again.
23:29:40Anna Stoppato: many solutions, again, which is the problem. More or less, the problems are the same that we have in gas turbine, and are related to the different combustion that hydrogen has with respect to air. So again, problems related to the…
23:46:00Anna Stoppato: Explosion limits, which are very higher for hydrogen.
23:50:200Anna Stoppato: The different, volume, for the same energy content.
23:56:50Anna Stoppato: And,
23:58:60Anna Stoppato: the different behavior, again, of the flame, the limits, and the maximum temperature. Again, they are moving on the same direction, also for internal combustion engines, and also in that case, there are, again, some solutions which try to use the oxygen instead of hydrogen, instead of air, in order
24:20:770Anna Stoppato: And again, but these are farther than here, they are trying to have a close circuit close, also for the internal combustion engines.
24:31:910Anna Stoppato: Okay, hydrogen, oxygen, and all we… in this case, we need to eliminate only a small portion of water. The other part of the fluid there can be recycled in a closed circuit.
24:48:970Anna Stoppato: Again, this must be, this must be, studied. Okay, so, these are the main points. The next lesson, you will have an expert related to combustion, so all the things that I only…
25:05:50Anna Stoppato: Whoa.
25:07:200Anna Stoppato: I give only a small information, and since we focus on the operation of the gas turbine, will be explaining it, you know that for hydrogen, but…
25:18:390Anna Stoppato: you will, have some more information. There were some projects also clo… not closed… that, arrived to the commercialization and also to the use in the buildings of hydrogen boilers, so…
25:32:870Anna Stoppato: He will explain you, the problems related to this. Okay, I… okay, I will put… I put the… the slides, I will add the slides with the…
25:45:920Anna Stoppato: with the TS diagram, and also with the… with this… okay, I prefer to start it with my picture, because we draw together, but I will add also the official picture.
26:00:50Anna Stoppato: From the, developers of this,
26:03:900Anna Stoppato: of this circle. Okay, so see you, two days.